Theaetetus

Plato · a new plain-English translation from the Greek

EUCLIDES: Just in from the country, Terpsion, or have you been back a while? TERPSION: A fair while. And I was looking for you in the marketplace, wondering why I couldn't find you. EUCLIDES: Because I wasn't in the city. TERPSION: Where, then? EUCLIDES: On my way down to the harbor I ran into Theaetetus being carried from Corinth, from the army camp, on his way to Athens. TERPSION: Alive or dead? EUCLIDES: Alive—but only just. He's in a bad way from some wounds, but what's really taking hold of him is the sickness that broke out in the army. TERPSION: Not the dysentery? EUCLIDES: Yes. TERPSION: What a man to have in danger. EUCLIDES: A fine and noble one, Terpsion. Just now, in fact, I was hearing people praising him warmly for his conduct in the battle. TERPSION: Nothing strange in that—it would be far more astonishing if he weren't that kind of man. But why didn't he stop here in Megara? EUCLIDES: He was in a hurry to get home. I begged him, I urged him, but he wouldn't hear of it. So I saw him on his way, and walking back I found myself remembering Socrates and marveling at how prophetic he was—about this man, among so much else. I believe it was shortly before his death that he met Theaetetus, then just a boy, and after spending time with him and talking with him, he was deeply impressed by his nature. When I went to Athens, he recounted to me the conversations he'd had with him—well worth hearing—and said the boy was absolutely bound to become someone of note, if he lived to grow up. TERPSION: And he spoke the truth, it seems. But what were those conversations? Could you recount them?

EUCLIDES: No, by Zeus—not from memory, not off the top of my head. But I made notes right away, as soon as I got home, and later, at my leisure, I wrote it out as I recalled it; and every time I went to Athens I would ask Socrates again about whatever I hadn't remembered, and correct it when I got back here. So by now I have practically the whole conversation written down. TERPSION: True—I've heard you say so before, and I've always meant to ask you to show it to me, but I've dawdled until now. Well, what's stopping us from going through it right away? I certainly need a rest anyhow, after coming in from the country. EUCLIDES: For that matter, I walked Theaetetus as far as Erineum myself, so I wouldn't mind a rest either. Let's go, and while we rest, the boy will read to us. TERPSION: Good idea. EUCLIDES: Here's the book, Terpsion. Now, I wrote the conversation out this way: not with Socrates narrating it to me, as he actually told it, but as if he were talking directly with the people he said he'd talked with—he said it was with Theodorus the geometer and with Theaetetus. So that the narrative bits in between wouldn't clutter the written version—the 'and I said' or 'and I remarked' whenever Socrates was speaking, or, about the person answering, that 'he agreed' or 'he wouldn't grant it'—I cut all that out and wrote it as if he were conversing with them himself. TERPSION: Nothing wrong with that, Euclides. EUCLIDES: Well then, boy, take the book and read. SOCRATES: If I cared more about the people of Cyrene, Theodorus, I'd be asking you about things there and about them—whether any of the young men over there are devoting themselves to geometry or any other branch of philosophy. But as it is, I love them less than I love these people here, and I'm more eager to know which of our own young men show promise of turning out well. That's what I keep an eye on myself, as far as I can, and I ask the others too—anyone I see the young men choosing to spend time with. And no small number of them gather around you, and rightly so: you deserve it, for geometry and for much else. So if you've come across anyone worth mentioning, I'd be glad to hear it.

THEODORUS: Well, Socrates, it's certainly worth my telling and your hearing what a boy I've come across among your citizens. If he were beautiful, I'd be very afraid to say so, in case someone thought I was in love with him. But as it is—and don't be annoyed with me—he is not beautiful: he resembles you, with the snub nose and the bulging eyes, though he has them less than you do. So I can speak without fear. I tell you, of all the boys I've ever met—and I've been around a great many—I've never yet noticed one so astonishingly gifted by nature. To be quick to learn, as few others are, and yet exceptionally gentle, and on top of that brave beyond anyone—I wouldn't have thought that combination could exist, and I don't see it occurring. The sharp ones like him, the quick-witted, the ones with good memories, are mostly also quick to flare up; they go darting about like ships without ballast, and grow up more manic than manly, while the steadier sort come to their studies sluggish somehow, loaded down with forgetfulness. But this one moves toward his lessons and inquiries so smoothly, so surely, so effectively, and with such perfect gentleness—like a stream of oil flowing without a sound—that it's a wonder someone his age gets these things done that way. SOCRATES: Good news. And whose son is he, of our citizens? THEODORUS: I've heard the name, but I don't remember it. But he's the middle one of these boys coming toward us. He and some companions of his were just oiling themselves in the outer track, and now that they're done, I think they're coming this way. See if you know him. SOCRATES: I know him. He's the son of Euphronius of Sunium—very much, my friend, the sort of man you describe this boy to be, and well thought of generally; what's more, he left a very large fortune. But I don't know the boy's name. THEODORUS: Theaetetus, Socrates—that's his name. As for the fortune, I believe some trustees have run through it. Yet even so, he's astonishingly generous with money, Socrates. SOCRATES: A noble fellow, by your account. Ask him to come and sit here with us. THEODORUS: I will. Theaetetus—over here, next to Socrates. SOCRATES: Yes, do, Theaetetus, so I can examine my own face and see what it looks like—Theodorus says it resembles yours. Now, suppose each of us had a lyre and he said they were tuned alike: would we take his word for it right away, or would we look into whether he was a musician when he said it? THEAETETUS: We'd look into it. SOCRATES: And if we found he was, we'd believe him; if he had no music in him, we wouldn't? THEAETETUS: True.

SOCRATES: But now, I take it, if we care at all about this likeness of faces, we need to consider whether he speaks as one with a painter's eye or not. THEAETETUS: I think so. SOCRATES: Well, is Theodorus a painter? THEAETETUS: Not as far as I know. SOCRATES: Nor a geometer either? THEAETETUS: Of course he is, Socrates. SOCRATES: And an astronomer, and a calculator, and a musician—everything that belongs to education? THEAETETUS: I'd say so. SOCRATES: Then if he says we're alike in some feature of our bodies, whether in praise or blame, it's hardly worth paying him much attention. THEAETETUS: Perhaps not. SOCRATES: But what if he praised the soul of one of us for virtue and wisdom? Wouldn't the one who hears the praise be right to be eager to examine the one praised, and the other be right to show himself off willingly? THEAETETUS: Certainly, Socrates. SOCRATES: Then it's time, my dear Theaetetus, for you to show yourself and for me to examine. Because I assure you, Theodorus has praised many people to me, foreigners and citizens both, and he's never yet praised anyone the way he praised you just now. THEAETETUS: That would be fine, Socrates—but watch out he wasn't joking. SOCRATES: That's not Theodorus's way. Don't back out of what we've agreed on the pretext that he was joking, or he may be forced to testify—no one is going to charge him with perjury, after all. So take heart and stand by the agreement. THEAETETUS: Well, I must, if that's what you think. SOCRATES: Tell me, then: you're learning some geometry from Theodorus? THEAETETUS: I am. SOCRATES: And astronomy too, and harmonics and calculation? THEAETETUS: I'm doing my best, anyway. SOCRATES: So am I, my boy—from him and from anyone else I think knows something about these things. Still, though I manage well enough with them in general, there's one small point I'm stuck on, which I need to examine with you and these others. Tell me: isn't learning becoming wiser about the thing one is learning? THEAETETUS: Of course. SOCRATES: And it's by wisdom, I take it, that the wise are wise. THEAETETUS: Yes. SOCRATES: And does that differ at all from knowledge? THEAETETUS: Does what differ? SOCRATES: Wisdom. Aren't people wise about exactly the things they have knowledge of? THEAETETUS: Well, yes. SOCRATES: So knowledge and wisdom are the same thing? THEAETETUS: Yes.

SOCRATES: Well, that's exactly what I'm stuck on and can't adequately grasp on my own: knowledge—what in the world is it? So can we say what it is? What do you all say? Which of us will speak first? Whoever misses—and whoever keeps missing—shall 'sit down and be donkey,' as the children say in their ball game; and whoever comes through without a miss shall be our king and command us to answer whatever he pleases. Why the silence? Theodorus, I hope my love of argument isn't making me rude, in my eagerness to get us talking and make us friendly and conversable with one another? THEODORUS: Not at all, Socrates—nothing rude in that. But do tell one of the boys to answer you. I'm unused to this kind of discussion, and I'm past the age for getting used to it. It would suit these boys, though, and they'd improve much more by it; youth truly has room to grow in everything. So don't let Theaetetus off—keep questioning him, as you began. SOCRATES: You hear what Theodorus says, Theaetetus. You won't want to disobey him, I imagine—and it wouldn't be right for a younger man to disobey a wise man's instructions in matters like this. So speak up, well and nobly: what do you think knowledge is? THEAETETUS: Well, I must, Socrates, since you both insist. And in any case, if I do slip somewhere, you'll set me straight. SOCRATES: Certainly—if we're able. THEAETETUS: Then I think that the things one could learn from Theodorus are knowledges—geometry and the ones you went through just now—and then again shoemaking and the crafts of the other artisans: all of them, and each of them, are nothing other than knowledge. SOCRATES: Nobly and open-handedly done, my friend! Asked for one thing, you give many—a rich variety instead of something simple. THEAETETUS: What do you mean by that, Socrates? SOCRATES: Perhaps nothing—but I'll tell you what I think. When you say 'shoemaking,' you mean nothing other than knowledge of the making of shoes? THEAETETUS: Nothing else. SOCRATES: And when you say 'carpentry'? Anything other than knowledge of the making of wooden furnishings? THEAETETUS: No, only that. SOCRATES: So in both cases, you're specifying what each knowledge is of? THEAETETUS: Yes. SOCRATES: But that wasn't what was asked, Theaetetus—what knowledge is of, or how many knowledges there are. We didn't ask because we wanted to count them, but to grasp knowledge itself: what in the world it is. Or am I talking nonsense? THEAETETUS: No, you're exactly right.

SOCRATES: Now consider this too. Suppose someone asked us a plain, ordinary question -- say, about clay, what it is -- and we answered him: there's the clay potters use, and the clay used for oven-makers, and the clay used by brickmakers. Wouldn't that be ridiculous? THEAETETUS: Maybe. SOCRATES: For one thing, we'd be assuming the questioner understands, just from our answer, what "clay" means, whether we add "the kind doll-makers use" or any other craftsman's kind. Or do you think anyone understands the name of a thing when he doesn't know what the thing itself is? THEAETETUS: Not at all. SOCRATES: So someone who doesn't know what knowledge is doesn't understand "knowledge of shoemaking" either. THEAETETUS: No, he doesn't. SOCRATES: So anyone who doesn't grasp knowledge doesn't grasp shoemaking, or any other craft. THEAETETUS: That's right. SOCRATES: So it's a ridiculous answer, when someone is asked what knowledge is, to answer with the name of some craft -- since he's naming knowledge of some particular thing, when that wasn't the question. THEAETETUS: So it seems. SOCRATES: And besides, when he could have given a plain, short answer, he wanders off down an endless road. Take the question about clay -- it would have been plain and simple to say that clay is earth mixed with liquid, and let go of whose clay it is. THEAETETUS: Put that way, Socrates, it does look easy. But I think you're asking the same kind of question that came up recently between me and my friend here, this other Socrates, when we were talking. SOCRATES: What sort of question, Theaetetus? THEAETETUS: Theodorus here was working something out for us about powers -- showing, for the square of three feet and the square of five feet, that they aren't commensurable in length with the one-foot square, and going through them one by one up to the square of seventeen feet, where for some reason he got stuck. Since the powers seemed endless in number, it occurred to us to try to gather them into one thing, some single name to call all these powers by. SOCRATES: And did you find something like that? THEAETETUS: I think we did -- see what you make of it yourself. SOCRATES: Go on. THEAETETUS: We split all number into two kinds. The kind that can come out as an equal number multiplied by itself we likened in shape to a square, and called it square, or equal-sided. SOCRATES: Very good so far.

THEAETETUS: Now the number in between -- the kind that includes three and five and every number that can't come out as an equal multiplied by itself, but only comes out as a smaller number taken more times or a larger number taken fewer times, so that it's always bounded by a larger side and a smaller side -- that kind we likened to an oblong shape, and called it oblong number. SOCRATES: Excellent. So what came next? THEAETETUS: All the lines that square off the equal-sided plane number, we marked off as length; and those that square off the oblong number, we called powers, since they aren't commensurable in length with the others, but only in the plane areas they can produce. And there's another such distinction for solids. SOCRATES: Best of anyone, my boys! It seems to me Theodorus won't be liable for false testimony after all. THEAETETUS: And yet, Socrates, what you're asking about knowledge I couldn't answer the way I answered about length and power -- though you seem to me to be after just that sort of thing. So once again Theodorus turns out to have spoken falsely. SOCRATES: Well now -- if he'd praised you for running and said he'd never met a young man so fast, and then you raced the fastest man in his prime and lost, do you think his praise would have been any less true? THEAETETUS: Not at all. SOCRATES: And knowledge -- do you think it's some small thing to track down, as I was just saying, and not a task for the very best? THEAETETUS: By Zeus, I do think it's a task for the very best, the very hardest. SOCRATES: Then take heart about yourself, and believe Theodorus, and be eager, every way you can, to get hold of an account of knowledge, along with everything else, of what it actually is. THEAETETUS: As far as eagerness goes, Socrates, it will show itself. SOCRATES: Come then -- you set us off well just now -- try, imitating the answer about powers, the way you gathered those, many as they are, under one form: try in the same way to address the many kinds of knowledge with one account. THEAETETUS: But I assure you, Socrates, I've tried many times to work this out myself, hearing the questions reported from you. But I can't persuade myself that I've said anything adequate, nor have I heard anyone else say it the way you keep urging -- and yet I can't shake off caring about it either. SOCRATES: That's because you're in labor, dear Theaetetus -- you're not empty, you're pregnant. THEAETETUS: I don't know about that, Socrates. I'm just telling you what I feel.

SOCRATES: Then, you absurd boy, haven't you heard that I'm the son of a midwife, a fine, sturdy woman named Phaenarete? THEAETETUS: I have heard that. SOCRATES: And have you heard that I practice the same trade? THEAETETUS: Not at all. SOCRATES: Well, know that I do -- only don't give me away to the others. It's a secret, my friend, that I have this skill. People, not knowing it, don't say this about me, but they do say I'm the strangest of men and that I get people stuck. Have you heard that too? THEAETETUS: I have. SOCRATES: Shall I tell you the reason? THEAETETUS: By all means. SOCRATES: Think through the whole business of midwives, and you'll grasp what I'm after more easily. You know, I suppose, that none of them still attends other women in labor while she herself is capable of conceiving and bearing -- only those who are already past childbearing do the delivering. THEAETETUS: Quite so. SOCRATES: And the reason for that, they say, is Artemis -- since she was allotted care of childbirth though she herself never bears children. She didn't grant midwifery to the barren, since human nature is too weak to master a skill in something it has no experience of; but to those who, through age, no longer bear, she assigned it, honoring their likeness to herself. THEAETETUS: That's likely. SOCRATES: And isn't this too likely, even necessary -- that midwives are better than anyone else at recognizing who is pregnant and who isn't? THEAETETUS: Quite so. SOCRATES: And more than that -- by giving drugs and chanting charms, midwives can stir up labor pains, and, if they choose, make them gentler; they can bring on birth for women having a hard time of it; and if it seems best to cause a miscarriage while it's still early, they do that too. THEAETETUS: That's true. SOCRATES: Have you noticed this about them as well -- that they're also the cleverest matchmakers, since they're thoroughly wise about knowing which woman ought to be paired with which man so as to produce the best children? THEAETETUS: I didn't know that at all. SOCRATES: Well, know that they take more pride in that than in cutting the cord. Think about it -- do you suppose it belongs to one craft or a different one, to tend and gather the crops of the earth, and also to know which soil suits which plant and seed? THEAETETUS: No -- the same craft. SOCRATES: And for a woman, my friend, do you think it's one craft for that and a different one for the gathering? THEAETETUS: That doesn't seem likely.

SOCRATES: No, it isn't. But because of the unjust, unskilled way of bringing a man and woman together -- which goes by the name of pimping -- midwives avoid matchmaking too, being women of honor, afraid of falling under that same charge on that account; since it's really only the true midwives who are fit to match couples correctly. THEAETETUS: So it appears. SOCRATES: That, then, is the extent of what midwives do -- and it's less than what I do. For it isn't the case with women that they sometimes bear phantoms and sometimes real children, with the difference hard to tell; if it were, distinguishing the true from the false would be the greatest and finest work of midwives -- don't you think? THEAETETUS: I do. SOCRATES: Well, my art of midwifery has everything theirs has, but differs in that I attend men, not women, and I watch over souls in labor, not bodies. And the greatest thing about my art is this: it's able to test in every way whether the young mind is bringing forth a phantom, something false, or something fertile and true. For this too belongs to me, just as it does to midwives: I myself am barren of wisdom. And the charge many have already brought against me -- that I question others but never state my own views about anything, because I have nothing wise in me -- that charge is true. The reason for it is this: the god compels me to serve as midwife, but has forbidden me to give birth. So I myself am not at all wise, nor do I have any discovery of my own to show, born of my own soul. But those who keep my company -- some seem quite stupid at first, yet as our association goes on, all of them, those the god allows, make progress that's astonishing, both to themselves and to others. And it's plain that this happens though they never learn anything from me -- they discover many fine things themselves, out of themselves, and simply bring them to birth. But the delivery is the work of the god and of me. Here's how you can see it: many, not understanding this, have taken the credit to themselves and thought little of me, and, either on their own or persuaded by others, have left me too soon. And once gone, they've miscarried the rest through bad company, and lost what I helped bring to birth by raising it badly, valuing lies and phantoms above the truth, until in the end they seemed, to themselves and everyone else, to be fools.

SOCRATES: Aristides, son of Lysimachus, was one of these, and a great many others besides. When they come back begging for my company again, doing extraordinary things to get it, sometimes the sign that comes to me forbids me to spend time with them, sometimes it allows it, and then they make progress again. Now, those who keep company with me suffer this same thing that women in labor do: they're in pain and filled with confusion, night and day, far more than women are -- and it's my art that can rouse this pain or put it to rest. So much for those. But there are others, Theaetetus, who don't seem to me to be pregnant at all in any way; and once I see they have no need of me, I very kindly play matchmaker for them, and, if I may say so with the god's blessing, I'm quite good at guessing whose company would do them good. Many of these I've given over to Prodicus, and many to other wise and inspired men. I've gone on at such length, my excellent friend, for this reason: I suspect that you, as you think yourself, are in labor with something inside you. So come to me as to the son of a midwife, one who is himself skilled in midwifery, and do your best to answer whatever I ask in whatever way you can. And if, as I examine what you say, I judge it to be a phantom and not true, and quietly take it from you and throw it away, don't get angry the way first-time mothers do over their children. Many, my friend, have gotten so worked up at me that they're truly ready to bite, whenever I remove some piece of nonsense from them -- they don't think I'm doing it out of good will, being far from knowing that no god means humans harm, and that I do nothing of the sort out of ill will either; it's simply not permitted for me to let a falsehood stand and hide the truth away. So once more from the beginning, Theaetetus -- try to say what knowledge is. And never say you can't. For if the god is willing, and you play the man, you will be able. THEAETETUS: Well, Socrates, with you urging me on like that, it would be shameful not to do everything I can to say what I have to say. It seems to me that someone who knows something perceives the thing he knows, and as it appears to me right now, knowledge is nothing other than perception. SOCRATES: Well said, and bravely, my boy -- that's how one ought to speak, stating one's view plainly. But come, let's examine it together, and see whether it's something fertile, or just wind. Knowledge, you say, is perception? THEAETETUS: Yes.

SOCRATES: You seem, though, to have stated no small account of knowledge — indeed the very one Protagoras used to give. He put it a different way, but it comes to the same thing. He says, somewhere, that man is the measure of all things — of the things that are, that they are, and of the things that are not, that they are not. You've read that, surely? THEAETETUS: I've read it, many times. SOCRATES: Then he means something like this: as each thing appears to me, so it is for me, and as it appears to you, so it is for you — and you and I are both 'man.' THEAETETUS: Yes, that's what he says. SOCRATES: It stands to reason a wise man wouldn't talk nonsense. So let's follow him. Isn't it true that sometimes, when the same wind blows, one of us feels cold and the other doesn't — one a little, the other a lot? THEAETETUS: Very much so. SOCRATES: Then are we going to say the wind itself, in itself, is cold or not cold? Or will we go along with Protagoras — that it's cold for the one who feels cold, and not for the one who doesn't? THEAETETUS: It looks that way. SOCRATES: And it appears that way to each of them too? THEAETETUS: Yes. SOCRATES: And 'appearing' is 'perceiving'? THEAETETUS: It is. SOCRATES: So appearance and perception are the same thing in matters of heat and everything of that kind. Whatever each person perceives, that is — apparently — how things are for him. THEAETETUS: It looks that way. SOCRATES: So perception is always of what is, and, being knowledge, it can't be false. THEAETETUS: So it seems. SOCRATES: Then, by the Graces, was Protagoras some kind of all-round genius, who tossed this out to the common rabble like us as a riddle, while telling his students the truth in secret? THEAETETUS: What do you mean by that, Socrates? SOCRATES: I'll tell you — and it's no small account either. It's this: that nothing is, in itself, just one thing — you couldn't even correctly call anything by any particular name at all — but if you call something big, it will turn out to look small too, and if heavy, light, and so on for everything, on the ground that nothing is one thing, or of any particular sort, or any quantity at all. It's out of motion and change and mixture with one another that all the things we say 'are' come to be — and we're wrong to call them that, since nothing ever simply is; everything is always coming to be. And on this point all the wise men, in a row, agree — except Parmenides — Protagoras, Heraclitus, Empedocles, and, among the poets, the top men of each genre: Epicharmus in comedy, Homer in tragedy. Homer, who spoke of 'Ocean, the begetter of gods, and Tethys their mother,' meant that all things are the offspring of flux and motion. Or don't you think that's what he's saying? THEAETETUS: I do.

SOCRATES: Who, then, could stand up against so vast an army with Homer as its general, and not end up looking ridiculous? THEAETETUS: It wouldn't be easy, Socrates. SOCRATES: No, it wouldn't, Theaetetus. And here's more evidence for the theory: what seems to be, and coming-to-be, are produced by motion, while not-being and perishing come from rest. Heat itself — fire, which generates and governs everything else — is itself generated by friction and motion; and those are both kinds of motion. Aren't these the ways fire comes to be? THEAETETUS: Yes, they are. SOCRATES: And the whole race of living things grows out of these same processes. THEAETETUS: Of course. SOCRATES: And again — doesn't the condition of our bodies waste away under rest and idleness, but get preserved, largely, by exercise and movement? THEAETETUS: Yes. SOCRATES: And the condition of the soul — doesn't it acquire learning and improve and stay sound through study and practice, which are both motions, while under rest — meaning lack of practice and lack of learning — it learns nothing, and forgets whatever it did learn? THEAETETUS: Very much so. SOCRATES: So motion is the good, for soul and body alike, and rest is the opposite? THEAETETUS: So it seems. SOCRATES: Shall I go on — windless calms, stillness of the sea, and all such things — how stillness rots things and destroys them, while the opposite preserves them? And to cap it all, I'll force in — I'll drag in — the golden chain, which Homer means nothing other than the sun: showing that as long as the heavenly revolution and the sun keep moving, everything among gods and men exists and is preserved, but if that came to a stop, as if bound fast, everything would be destroyed, and it would all become — as the saying goes — turned upside down. THEAETETUS: Well, Socrates, it does seem to me that this is what he's showing. SOCRATES: Then take it this way, my excellent friend. Start with the eyes. What you call the color white — don't think of it as some separate thing existing outside your eyes, or even inside your eyes; don't assign it any place at all. If you did, it would already have a fixed position, would stay put, and wouldn't be in a process of coming-to-be. THEAETETUS: Then how should I think of it?

SOCRATES: Let's follow the argument we just gave, and posit that nothing is, in itself, a single, self-standing thing. On this view, black and white and any other color will appear to have come into being out of the collision of the eye with the appropriate motion, and what we call 'the color' in each case will be neither the agent doing the striking nor the thing struck, but something in between, particular to each occasion. Or would you insist that whatever color appears to you, the same appears to a dog, or to any other creature? THEAETETUS: No, by Zeus, I wouldn't. SOCRATES: Well then — does anything appear the same to another person as it does to you? Are you confident of that — or far more confident that it isn't even the same to you yourself, since you're never in the same state as yourself from one moment to the next? THEAETETUS: That seems more likely to me than the other. SOCRATES: Well then — if the thing we measure against, or touch, were itself big, or white, or hot, it could never become something different by coming into contact with something else, without itself changing. And conversely, if the thing doing the measuring or touching were itself any of these fixed things, then it too couldn't become something different just because something else approached it or was affected, without itself being affected. As it stands, my friend, we're being forced, rather too easily, into saying all sorts of strange and ridiculous things — the very things Protagoras, and anyone arguing his position, would say. THEAETETUS: How so? What sort of things do you mean? SOCRATES: Take a small example and you'll see everything I mean. Say there are six knucklebones: if you set four beside them, we say they are more than the four — half again as many — but if you set twelve beside them, we say they are fewer — half as many. And no other way of speaking is tolerable. Or would you tolerate it? THEAETETUS: I would not. SOCRATES: Well then — if Protagoras, or anyone else, asked you: Theaetetus, can anything become bigger or more, in any way other than by being increased? What would you answer? THEAETETUS: If I answer according to what seems true given this question, Socrates, I'd say no, it can't. But if I answer with the earlier question in mind, being careful not to contradict myself, I'd say yes, it can. SOCRATES: Well said, by Hera, my friend — a truly inspired answer! Though it seems that if you answer 'yes, it can,' something worthy of Euripides will follow: our tongue will be unrefuted, but our mind will not. THEAETETUS: True. SOCRATES: Now if you and I were clever and wise, having examined everything in our minds down to the last detail, we'd already be sparring with each other out of sheer surplus skill, colliding our arguments against each other's like sophists in a contest of that sort. But as it is, being ordinary people, we'll want first to look at the things themselves, to see what they really are that we have in mind — whether they agree with one another or not at all. THEAETETUS: That is exactly what I would want.

SOCRATES: And so would I. Since that's how things stand, shall we, calmly, as people with plenty of leisure, go back and examine ourselves again — not out of irritability, but really testing ourselves — as to what in the world these appearances within us are? Looking at them first, I think we'll say that nothing could ever become bigger or smaller, either in bulk or in number, so long as it remains equal to itself. Isn't that so? THEAETETUS: Yes. SOCRATES: Second: whatever has nothing added to it and nothing taken away from it never increases or decreases, but always stays equal. THEAETETUS: Quite so. SOCRATES: And third — isn't it also true that whatever was not before, but is later, cannot be so without having come to be and being in the process of coming to be? THEAETETUS: It does seem so. SOCRATES: These three admissions, I think, conflict with one another in our minds when we talk about the knucklebones, or when we say that I, being the age I am, without growing or undergoing the opposite, am, within a year, bigger than you, who are young now, and later smaller — not because anything has been taken away from my bulk, but because you have grown. For I am later what I was not before, without having become so — since it's impossible to become something without the process of coming to be — yet without losing any of my bulk I could never become smaller. And countless other things like this happen too, if we're going to accept these premises. You're following me, I take it, Theaetetus — you don't strike me as inexperienced in these matters. THEAETETUS: Yes, by the gods, Socrates — I'm astonished, overwhelmingly, at what these things could possibly be, and sometimes, looking straight at them, I really do feel dizzy. SOCRATES: Theodorus, my friend, seems to have judged your nature well. This feeling — wonder — is very much the mark of a philosopher; philosophy has no other starting point than this, and whoever said Iris was the child of Thaumas was tracing her lineage well. But do you understand yet why these things are as they are, given what we say Protagoras means — or not yet? THEAETETUS: Not yet, I think. SOCRATES: Then will you be grateful to me if I help you dig out, along with you, the truth hidden in the thinking of a man — or rather, of several famous men? THEAETETUS: Of course I'll be grateful, very much so. SOCRATES: Look around, then, and make sure none of the uninitiated are listening. These are the people who think nothing is real except what they can grip firmly with both hands — who won't accept actions, or comings-to-be, or anything invisible, as part of reality.

THEAETETUS: Well, Socrates, the men you're describing certainly sound tough and hard-headed. SOCRATES: They are, my boy — thoroughly graceless. But there are others, much subtler, whose mysteries I'm about to reveal to you. Their starting point, from which everything we've just been saying hangs, is this: that everything is motion, and there is nothing besides motion — but motion comes in two kinds, each infinite in number, one having the power to act, the other to be acted upon. Out of their meeting and rubbing against each other come offspring, infinite in number, but always born in pairs — on one side something perceived, on the other a perception, always emerging and being generated together with the thing perceived. Our perceptions have names like these: sight, hearing, smell, feelings of cold and of heat, and also pleasures and pains, desires and fears, and others besides — countless ones without names, and a great many that do have names. And the class of perceptible things, in turn, is born alongside each kind of perception: colors of every sort alongside sight, sounds likewise alongside hearing, and other perceptible things akin to each of the other perceptions. Now what is this story meant to tell us, Theaetetus, in relation to what came before? Do you see it? THEAETETUS: Not entirely, Socrates. SOCRATES: Then pay attention and see if it comes together. What it means to say is that all these things, as we've been saying, are in motion, but there is speed and slowness in their motion. Whatever is slow keeps its motion fixed in place, directed at what comes near it, and in that way it generates — and what is generated in this way moves faster, since it is carried along, and motion is, by nature, in that carrying. So whenever an eye, and some other thing commensurate with it, come near each other and generate whiteness, together with the perception connatural to it — things that would never have come to be if either of those two had gone toward something else instead — then, while sight travels from the eyes and whiteness travels from the thing that co-produces the color, in the space between them, the eye becomes filled with sight and so comes to see, and becomes not sight itself but a seeing eye; while the thing that joined in generating the color becomes saturated with whiteness, and becomes not whiteness itself but a white thing — whether it turns out to be a piece of wood, a stone, or whatever else happens to be colored with that color.

SOCRATES: And we should think the same way about everything else — hard, hot, all of it. None of these things is anything in itself, as we said before; they all come to be, in all their varieties, out of the interaction of things in motion. Because even the notion of a fixed 'agent' or 'patient' — something that acts and something acted upon, each taken separately — doesn't hold up, as the wise say. Nothing is an agent until it meets something to act on, and nothing is acted upon until it meets something acting; and whatever meets one thing and acts turns out, when it collides with something else, to be acted upon instead. So out of all this — which is exactly what we said from the start — nothing is ever one thing, fixed in itself, but always something coming-to-be for something else, and 'being' has to be struck out everywhere, even though force of habit and plain ignorance have just made us use the word ourselves, repeatedly. But that's not allowed, according to the theory of the wise — we mustn't grant that anything is 'something,' or 'someone's,' or 'mine,' or 'this,' or 'that,' or give it any name that makes it stand still; we should speak in accordance with nature and say things are 'coming to be,' 'being made,' 'perishing,' 'changing' — since anyone who makes something stand still in speech is easily refuted. And this has to apply piece by piece and also to things gathered into groups — which is the kind of grouping people label 'a man' or 'a stone' or any given animal or kind. Well, Theaetetus, does all this seem pleasant to you? Would you taste it and find it agreeable? THEAETETUS: I really don't know, Socrates — in fact I can't even tell about you, whether you're saying what you actually think or just testing me. SOCRATES: You forget, my friend, that I myself know nothing and claim nothing of this sort as my own — I'm barren of such things. I act as midwife for you, and that's why I chant incantations and serve you tastes from each of the wise, until I've helped bring your own view out into the light. Once it's delivered, I'll examine whether it turns out to be wind or something with real substance. So take heart, be patient, and answer bravely and honestly whatever seems true to you about what I ask. THEAETETUS: Go on and ask, then. SOCRATES: Tell me again, then: does it please you to say that nothing simply is, but everything is always coming to be — good, beautiful, and all the things we just went through? THEAETETUS: Yes, for my part — hearing you lay it out this way, it strikes me as remarkably sound, and I think it has to be accepted just as you've explained it. SOCRATES: Then let's not leave out what's still missing. What remains concerns dreams, and illnesses — including madness — and all the cases of mishearing, misseeing, or misperceiving in some other way. You know, I suppose, that in all these cases the theory we just went through seems, by common agreement, to be refuted, since in them, more than anywhere, false perceptions occur in us — and far from it being true that what appears to each person also is, quite the opposite: none of the things that appear actually is.

THEAETETUS: That's very true, Socrates. SOCRATES: Then what theory is left, my boy, for someone who claims perception is knowledge, and that what appears to each person also is, for the one to whom it appears? THEAETETUS: I hesitate to say I have nothing to answer, Socrates, since you just scolded me for saying that very thing. But I honestly couldn't dispute that madmen and dreamers hold false beliefs, when some of them think they're gods, and others think they're birds and imagine themselves flying in their sleep. SOCRATES: Don't you also notice a further puzzle about these cases, especially about waking and dreaming? THEAETETUS: What puzzle? SOCRATES: One you've surely heard people raise before: what proof could someone offer, if asked right now, whether we're asleep and dreaming everything we're thinking, or awake and genuinely talking with each other? THEAETETUS: Really, Socrates, it's hard to see what proof one could give — everything lines up as if in matching pairs. The very conversation we're having now could just as well be something we imagine having in our sleep, and whenever we dream that we're telling our dreams, the resemblance between the two is uncanny. SOCRATES: So you see it's not hard to raise the dispute, since even whether we're awake or dreaming is disputable — and given that we spend roughly equal time in each state, in both cases our soul insists that whatever it currently believes is true beyond anything else, so that for equal stretches of time we claim these things are real, and equally we claim those other things are real, and we're just as adamant on both sides. THEAETETUS: Absolutely. SOCRATES: And doesn't the same reasoning apply to illness and madness too, except that the time involved isn't equal? THEAETETUS: Right. SOCRATES: Well then — will truth be decided by how much or how little time something lasts? THEAETETUS: That would be absurd in all sorts of ways. SOCRATES: But can you point to anything else clear enough to show which of these beliefs are true? THEAETETUS: I don't think so. SOCRATES: Then listen to me, and hear what those who define whatever seems true to someone as actually true for them would say about all this. I imagine they'd put the question this way: Theaetetus, whatever is entirely different from something else — could it possibly share any power at all with that other thing? And let's not assume that the thing we're asking about is the same in one respect and different in another — no, let's mean wholly different.

THEAETETUS: Then it's impossible for it to have anything the same, whether in power or in any other respect, when it is completely different. SOCRATES: And isn't it also necessary to grant that such a thing is unlike the other? THEAETETUS: I think so. SOCRATES: So if it happens that something becomes like or unlike something else — whether like itself or like something else — we'll say that in becoming like, it becomes the same, and in becoming unlike, it becomes different? THEAETETUS: Necessarily. SOCRATES: Now, didn't we say earlier that the things acting are many and unlimited, and likewise the things acted upon? THEAETETUS: Yes. SOCRATES: And also that one thing combined with another, and again with yet another, will generate not the same results but different ones? THEAETETUS: Certainly. SOCRATES: Then let's take you and me and everything else by the same reasoning — Socrates healthy, and Socrates sick again. Shall we say this one is like that one, or unlike it? THEAETETUS: Do you mean the sick Socrates as a whole, compared to the whole healthy Socrates? SOCRATES: You've grasped it exactly — that's just what I mean. THEAETETUS: Unlike, surely. SOCRATES: And therefore different, just as it's unlike? THEAETETUS: Necessarily. SOCRATES: And you'll say the same about Socrates asleep, and all the other cases we just went through? THEAETETUS: I will. SOCRATES: So each of the things whose nature it is to act on something — will it treat healthy Socrates as one thing to work on, and treat sick Socrates as another? THEAETETUS: Of course. SOCRATES: And in each of these two cases, we'll generate different results — I who am acted upon, and that thing which acts? THEAETETUS: Naturally. SOCRATES: So when I, being healthy, drink wine, it appears to me pleasant and sweet? THEAETETUS: Yes. SOCRATES: Because, following what we've already agreed, the agent and the patient generated sweetness together with a perception, both moving in tandem — the perception, coming from the side of the one acted upon, made the tongue perceiving, while the sweetness, coming from the wine and moving around it, made the wine both be and appear sweet to the healthy tongue. THEAETETUS: Yes, that's exactly what we agreed earlier. SOCRATES: But when I'm sick, in truth didn't it first meet a different me? For it approached someone unlike the other. THEAETETUS: Yes. SOCRATES: So this Socrates, in this condition, and the drinking of the wine, together generated something different again — a perception of bitterness around the tongue, and a bitterness coming to be and moving around the wine; and the wine becomes not bitterness but bitter, and I become not perception but one perceiving? THEAETETUS: Exactly so.

SOCRATES: So I myself will never become anything else in this same way of perceiving — for a perception of one thing is different from a perception of another, and it makes the perceiver different and other. Nor will that thing which acts on me, ever meeting something else, generate the same result and remain what it was — for by generating something different from something different, it will itself become different. THEAETETUS: That's so. SOCRATES: And I am not the same to myself, either, nor will that other thing be the same to itself. THEAETETUS: No, indeed. SOCRATES: But it's necessary that I become something's — mine, that is, of some object — whenever I come to be perceiving; for it's impossible to become one perceiving while perceiving nothing. And that other thing must become something's, too, whenever it comes to be sweet or bitter or anything of the sort — for it's impossible for it to become sweet without being sweet to someone. THEAETETUS: Absolutely. SOCRATES: So what's left to us, I think, is to be bound to each other — if we exist, to exist for each other, and if we come to be, to come to be for each other — since necessity binds our very being together, yet binds it to nothing else, not even to ourselves alone. So what's left is that we're bound together with one another. So whether someone speaks of 'being' or 'becoming,' he must say it is being or becoming for someone, or of something, or in relation to something; but 'being' or 'becoming' something on its own, in itself — that he must neither say himself, nor accept from anyone else who says it — as the argument we've gone through shows. THEAETETUS: Absolutely right, Socrates. SOCRATES: So then, since whatever acts on me belongs to me and to no one else, I'm the one who perceives it, and no one else? THEAETETUS: Of course. SOCRATES: So my perception is true for me — since it always belongs to my own being — and I am, as Protagoras says, judge of the things that are, that they are, for me, and of the things that are not, that they are not? THEAETETUS: So it seems. SOCRATES: So then, being free from falsehood and never stumbling in my thinking about the things that are or come to be, how could I fail to have knowledge of the very things I perceive? THEAETETUS: There's no way you could fail to. SOCRATES: So it's been beautifully said by you, that knowledge is nothing other than perception, and it all comes together into one — according to Homer and Heraclitus and the whole tribe of people like them, that everything moves like flowing streams; according to Protagoras, wisest of all, that man is the measure of all things; and according to Theaetetus, given all this, that perception becomes knowledge. Isn't that right, Theaetetus? Shall we call this newborn child yours, and my delivery of it? Or how do you put it? THEAETETUS: It has to be so, Socrates.

SOCRATES: This, then, it seems, we've finally managed to give birth to, whatever it actually turns out to be. But after the delivery, we really do need to run the child around in a circle in our discussion — the way people do at the naming ceremony — to make sure we're not missing that what's been born isn't worth raising at all, but is only wind and falsehood. Or do you think we absolutely must raise whatever's yours and not set it aside — or will you put up with seeing it examined and refuted, and not get too angry if someone, as with a firstborn, tries to take it away from you? THEODORUS: Theaetetus will put up with it, Socrates — he's not at all difficult that way. But in god's name, tell us in what way it isn't so. SOCRATES: You really are a lover of argument, Theodorus, and a good one, if you think I'm some kind of sack full of arguments, ready to pull one out easily and say that after all this isn't how things are. But you don't notice what's actually happening — that none of the arguments comes from me at all, but always from whoever is talking with me; I myself know nothing beyond a little — just enough to take an argument from another wise person and receive it fairly. And now I'll try to get this from our friend here, not say it myself. THEODORUS: You put it better that way, Socrates — do it so. SOCRATES: Do you know, then, Theodorus, what I find strange about your friend Protagoras? THEODORUS: What is it? SOCRATES: Everything else he's said pleases me very much — that whatever seems true to each person, is true for them. But I'm puzzled by the opening of his argument, that he didn't begin his book called Truth by saying that the measure of all things is a pig, or a dog-headed baboon, or some still stranger creature capable of perception — that would have been a truly grand and utterly contemptuous way to begin speaking to us, showing us that while we were admiring him for his wisdom as if he were a god, he was in fact no better in intelligence than a tadpole, let alone any other human being. What are we to say, Theodorus? If whatever each person judges true through perception really will be true for him, and no one can judge another's experience better than he can, nor is anyone in a better position to examine whether another's belief is right or wrong, but rather — as has been said many times — each person alone will judge his own beliefs, and all of them will be correct and true, then why on earth, my friend, is Protagoras so wise as to be rightly regarded as a teacher of others, and paid handsomely for it, while we are more ignorant and ought to go sit at his feet — when each of us is, in himself, the measure of his own wisdom? How can we avoid saying that Protagoras is just playing to the crowd with this? As for my own art of midwifery, and how much ridicule we bring on ourselves — and the whole practice of dialectic along with it — I say nothing. For isn't examining and trying to refute one another's impressions and opinions, when each person's opinions are correct, an enormous and endless piece of nonsense — if Protagoras's Truth really is true, and wasn't just speaking playfully from the inner sanctuary of his book?

THEODORUS: Socrates, he's a friend of mine, as you just said. So I wouldn't want Protagoras refuted through my agreeing to things, nor would I want to resist you against my own judgment. Take up Theaetetus again — he seemed to be following you quite gracefully just now. SOCRATES: Theodorus, if you went to Sparta and visited the wrestling grounds, would you think it fair to watch other men naked, some of them in poor shape, without stripping down yourself and showing your own form? THEODORUS: Well, what do you think, if they were going to let me off and be satisfied — just as I think I'll persuade you two to let me watch and not drag me, stiff as I already am, onto the mat, but wrestle instead with this younger, more supple fellow? SOCRATES: Well, Theodorus, if that's your pleasure, it's no trouble to me either, as the proverb goes. So back we go to our wise Theaetetus. Tell me, Theaetetus — about what we just went through — doesn't it strike you as strange that you should suddenly turn out to be, in wisdom, no worse than any man alive, or even any god? Or do you think Protagoras's 'measure' applies less to gods than to men? THEAETETUS: No, by Zeus, I don't — and that's exactly what puzzles me about your question. When we were going through how people say that what seems to each person is also true for the one it seems to, it struck me as very well put; but now it's suddenly flipped to the opposite. SOCRATES: That's because you're young, my dear boy — you're quick to catch the drift of a popular speech and let it persuade you. Protagoras, or someone speaking for him, will answer this: 'You fine fellows, old and young alike, sitting there making speeches together and dragging the gods into it — gods I steer clear of, both in speaking and writing, as to whether they exist or not — and you say what the crowd would gladly accept hearing, namely how terrible it would be if each human being were no better in wisdom than any random farm animal. But you offer no proof, no necessity whatsoever — you just rely on plausibility, and if Theodorus or any other geometer wanted to do geometry that way, he wouldn't be worth a thing. So you and Theodorus had better consider whether you're willing to accept arguments about matters this important resting on mere persuasiveness and plausibility.'

THEAETETUS: No, that isn't fair, Socrates — neither you nor we would say it was. SOCRATES: Then we must look at the question your argument and Theodorus's raises in another way, it seems. THEAETETUS: Yes, quite another way. SOCRATES: Let's look at it this way then: is knowledge the same thing as perception, or different? That's really what our whole discussion has been aiming at, and that's why we stirred up all these strange questions. Isn't that so? THEAETETUS: Absolutely. SOCRATES: Well then — shall we agree that whatever we perceive by seeing or hearing, we also know at that same moment? Take the case of foreigners whose language we don't yet understand — shall we say we don't hear them when they speak, or that we both hear and understand what they say? And again, people who don't know how to read, looking at written letters — shall we say they don't see them, or that they know them, since they see them? THEAETETUS: We'll say we know just this much of them, Socrates — the very thing we see and hear: the shape and color of the letters we both see and know, and the pitch, high or low, of the sounds we both hear and recognize; but what the grammar teachers and interpreters teach about them, that we neither perceive by seeing or hearing, nor do we know. SOCRATES: Excellent, Theaetetus — and it wouldn't be worth arguing with you about that, so that you can keep growing. But look at this other point coming up, and see how we're going to fend it off. THEAETETUS: What point is that? SOCRATES: This one: if someone asked, is it possible for a person who has come to know something, and still retains and preserves the memory of that very thing, not to know, at the moment he remembers it, that very thing he remembers? I'm being long-winded, it seems, but I just want to ask whether someone who has learned something and remembers it can fail to know it. THEAETETUS: How could that be, Socrates? That would be monstrous. SOCRATES: Am I talking nonsense, then? Consider: don't you say that seeing is perceiving, and that sight is a kind of perception? THEAETETUS: I do. SOCRATES: Then hasn't the man who saw something come to know that thing he saw, by the argument we just made? THEAETETUS: Yes. SOCRATES: And what about memory — you do mean something by it? THEAETETUS: Yes. SOCRATES: Memory of nothing, or of something? THEAETETUS: Of something, surely. SOCRATES: Of things he learned and perceived — things of that sort? THEAETETUS: Of course. SOCRATES: So whatever someone saw, he sometimes remembers it later? THEAETETUS: He remembers it. SOCRATES: Even with his eyes shut? Or does shutting his eyes make him forget it? THEAETETUS: That would be absurd to say, Socrates.

SOCRATES: And yet we must say it, if we're going to save our earlier position — otherwise it's gone. THEAETETUS: I suspect as much myself, by Zeus, though I can't quite grasp it fully — tell me how. SOCRATES: Like this: the man who sees, we say, has come to know the thing he sees, since sight and perception and knowledge have been agreed to be the same. THEAETETUS: Quite so. SOCRATES: But the man who saw, and came to know the thing he saw, if he shuts his eyes, remembers it but no longer sees it. Right? THEAETETUS: Yes. SOCRATES: But 'does not see' means 'does not know,' if indeed 'sees' means 'knows.' THEAETETUS: True. SOCRATES: So it follows that a man who has come to know something, and still remembers it, does not know it — since he doesn't see it. And we said that would be monstrous, if it happened. THEAETETUS: That's very true. SOCRATES: So something impossible turns out to follow, it seems, if one says that knowledge and perception are the same thing. THEAETETUS: It looks that way. SOCRATES: Then each of them must be called something different. THEAETETUS: I'm afraid so. SOCRATES: Then what in the world could knowledge be? It seems we must say it all over again from the beginning. And yet, Theaetetus, what are we even about to do? THEAETETUS: About what? SOCRATES: It strikes me that we're behaving like some worthless rooster, crowing in triumph and leaping away from the argument before we've actually won. THEAETETUS: How do you mean? SOCRATES: We seem to be acting like professional debaters — securing agreement on the use of words, being satisfied to have gotten the better of the argument by some trick like that, and, though we claim not to be contestants but philosophers, we don't notice that we're doing exactly what those clever men do. THEAETETUS: I still don't understand what you mean. SOCRATES: Well, let me try to explain what I have in mind. We asked whether someone who has learned something and remembers it can fail to know it, and, by showing that a man who saw something and then shut his eyes remembers it while not seeing it, we proved that he doesn't know it, even while he remembers it — which is impossible. And so the Protagorean myth is destroyed, and along with it your idea too, that knowledge and perception are the same thing. THEAETETUS: So it seems. SOCRATES: And yet, my friend, I don't think it would have gone this way if the father of the other myth were still alive — he would have put up quite a defense. As it is, we're trampling on it now that it's an orphan. Not even the guardians Protagoras left behind are willing to come to its aid — and Theodorus here is one of them. So it looks like we'll have to defend it ourselves, for justice's sake.

THEODORUS: It isn't really my job, Socrates — Callias, son of Hipponicus, is more the guardian of his ideas; we turned rather quickly from bare arguments toward geometry. Still, I'll be grateful to you if you defend him. SOCRATES: Well said, Theodorus. Consider, then, what my defense amounts to. One might agree to things even stranger than what we said before, if one doesn't pay close attention to the words — which is what we're mostly in the habit of doing, affirming and denying. Shall I explain it to you, or to Theaetetus? THEODORUS: To both of us together — but let the younger one answer; he'll be less embarrassed if he trips up. SOCRATES: Well, here's the most formidable question of all, and it runs something like this: is it possible for the same person, knowing something, not to know that very thing he knows? THEODORUS: Well, Theaetetus, what shall we answer? THEAETETUS: It's impossible, I should think. SOCRATES: Not if you're going to maintain that seeing is knowing. What will you do with an inescapable question — caught, as the saying goes, down a well — when a bold questioner covers one of your eyes with his hand and asks whether you see his cloak with the covered eye? THEAETETUS: I'll say no, not with that one — but with the other, yes. SOCRATES: So you both see and don't see the same thing at once? THEAETETUS: In a manner of speaking, yes. SOCRATES: 'That's not what I'm asking or claiming,' he'll say, 'I only asked whether the thing you know, you also don't know. But as it stands, you're shown to see a thing you don't see. And you've already agreed that seeing is knowing and not seeing is not knowing. So work out for yourself what follows from that.' THEAETETUS: Well, I work out that the consequence is the opposite of what I assumed. SOCRATES: And perhaps, my astonishing friend, you'd have run into even more trouble like that if someone had gone on to ask you whether it's possible to know something both sharply and dimly, to know it from close up but not from far away, to know the same thing both intensely and faintly, and a thousand other such things — the kind of ambush a mercenary skirmisher lying in wait with words would spring on you, once you'd set down knowledge and perception as the same, hurling in hearing and smelling and perceptions of that sort, refuting you relentlessly and never letting up, until, marveling at his much-vaunted cleverness, you found yourself entangled in his snares — and once he had you in his grip and bound fast, he could then ransom you for whatever price the two of you agreed on. So you might ask, what argument will Protagoras offer in his own defense? Shall we try to state it ourselves? THEAETETUS: By all means.

SOCRATES: All the points we've just been making in his defense, I think he'll charge straight at us, full of contempt, and say: 'So this is the celebrated Socrates — when a little child was asked whether the same person could remember and not know the same thing at the same time, he got frightened, and because he couldn't see ahead, he said no, and made a laughingstock of me in the argument. But the truth, Socrates, you laziest of men, is this: when you examine one of my positions by questioning, if the person questioned answers as I would have answered and stumbles, then I am refuted; but if he answers differently, then the one questioned is refuted, not I. For instance — do you really think anyone will grant you that a memory present in someone of what he once experienced is the same kind of experience as the one he had while actually experiencing it, now that he's no longer experiencing it? Far from it. Or again, will he hesitate to admit that it's possible for the same person to know and not know the same thing? Or if he's afraid of that, will he ever grant that a person who has changed is the same as he was before he changed — or rather, that he is even a single person and not many, indeed infinitely many, once change keeps occurring — if we really must be on our guard against catching each other out over mere words? No, my good man,' he'll say, 'come at what I actually mean more nobly, if you can, and refute this: that private perceptions do not arise for each of us, or that, granting they are private, what appears would be no more true for the one it appears to — or, if we must speak of 'being,' would be so for whomever it appears to. As for talking about pigs and baboons, not only are you yourself behaving like a pig, you're persuading your listeners to treat my writings that way too — and that's not well done. For I maintain that the truth is as I've written it: each of us is the measure of what is and what is not, yet one person differs enormously from another in just this respect, that different things are and appear to one than to another. And I am far from denying that there is such a thing as wisdom or a wise man — rather, I call wise precisely the man who, for any of us to whom bad things appear and are, can by a change make good things appear and be instead. Don't chase after my words, though — understand more clearly still what I mean, in this way. Recall what was said before: to the sick man, what he eats appears and is bitter, while to the healthy man it is and appears the opposite.'

SOCRATES: Well, we shouldn't try to make either of them wiser than the other — that isn't even possible — and we shouldn't say that the sick man is ignorant for judging as he does, while the healthy man is wise for judging differently. What's needed is a change from the one condition to the other, since the second state is better. And it's the same in education: one has to move from a worse condition to a better one. Only the doctor produces the change with drugs, while the sophist does it with words. It isn't that anyone ever takes a person who judges falsely and later makes him judge truly — that's not possible, since one cannot judge things that are not, nor anything other than what one is actually experiencing, and what one experiences is always true. Rather, I think, when someone is in a bad state of soul and judges things akin to that condition, a good state makes him judge other things of the same kind — things which some people, out of inexperience, call true appearances, while I call the one set better than the other, but not one bit truer. And as for the wise, my dear Socrates, I'm nowhere near calling them frogs — with respect to bodies I call them doctors, with respect to plants, farmers. For I say that these people too, instead of the bad sensations plants have when something in them is weak, instill good and healthy and true sensations in them; and likewise the wise and good public speakers make what is beneficial seem just to their cities instead of what is harmful. For whatever seems just and fine to a given city is just and fine for that city as long as it holds that belief. But the wise man makes what is beneficial seem — and be — in place of what was harmful for them in each such case. On the same reasoning, the sophist too, who can educate his students in this way, is wise and worth a great deal of money to those he has educated. And so it is true both that some people are wiser than others and that no one judges falsely, and you, whether you like it or not, must put up with being a 'measure' — for this is exactly how the argument holds together. Now if you can dispute this from the beginning, dispute it — set out a counter-argument. Or if you'd rather proceed by questioning, do that instead — there's no need to avoid it either; in fact a person of sense should pursue it above everything. Only do this: don't be unjust in your questioning. It would be quite absurd for someone who claims to care about virtue to do nothing but act unjustly in arguments.

SOCRATES: And one acts unjustly in this business whenever one doesn't keep contests and conversations separate — treating them as one and the same — playing and tripping people up as much as one can in the one, but in genuine conversation being serious and correcting one's partner, pointing out to him only those errors into which he has been led by himself or by earlier discussions. If you do this, the people who spend time with you will blame themselves for their own confusion and perplexity, not you, and they'll pursue you and love you, while hating and fleeing from themselves, toward philosophy, so that they may become different people and be rid of who they were before. But if you do the opposite, as most people do, the opposite will happen to you, and you'll turn those who spend time with you against philosophy itself once they're older. So if you're persuaded by me — as was said before — you'll approach the question calmly, without hostility or combativeness, but with real goodwill, and consider what we actually mean when we say all things are in motion, and that whatever seems so to each person and city, is so for that person or city. And from there you'll examine whether knowledge and perception are the same thing or different, rather than the way you were doing it just now — arguing from the ordinary usage of words and names, which most people drag about however it happens to suit them and thereby create all sorts of puzzles for each other. This much, Theodorus, I've contributed on behalf of your friend, to the best of my ability — a small offering from small resources. If he were still alive, he would have come to his own defense in far grander style. THEODORUS: You're joking, Socrates — you've defended the man quite vigorously. SOCRATES: Well said, my friend. And tell me — did you notice, when Protagoras was speaking just now and reproaching us for arguing against his position by playing on a child's fears, and calling it a kind of cheap cleverness, while praising the solemnity of his 'measure of all things' — did you notice that he was urging us to take his argument seriously? THEODORUS: Of course I noticed, Socrates. SOCRATES: Well then? Do you tell us to obey him? THEODORUS: Absolutely. SOCRATES: Then you see that everyone here except you is a child. So if we're going to obey the man, you and I need to question and answer each other and take his argument seriously, so he can't complain that we examined his argument as if playing games with mere boys. THEODORUS: But surely Theaetetus could follow a closely reasoned argument better than many men with big beards?

SOCRATES: Not better than you, though, Theodorus. So don't imagine that I have to defend your departed friend by every means, while you get no defense at all. Come now, my good man, follow along a little way — at least until we know whether it's really you who must be the measure where geometrical figures are concerned, or whether everyone is equally capable, like you, in astronomy and the other fields in which you're said to excel. THEODORUS: It isn't easy, Socrates, to sit beside you and refuse to give an account of oneself. I was talking nonsense a moment ago, saying you'd let me off without stripping down, and wouldn't force me the way the Spartans do — you seem to me to lean more toward Sciron. The Spartans tell a man either to leave or strip; but you seem to me to play the part of Antaeus rather — you don't let a man who approaches you go until you've forced him to strip and wrestle with you in argument. SOCRATES: You've compared my affliction very aptly, Theodorus — though I'm actually tougher than those two. Countless Heracleses and Theseuses, strong in argument, have already run into me and given me a fine thrashing, yet I don't give up one bit more for it — such is the strange passion that has taken root in me for this kind of exercise. So don't you begrudge me either — rub up against me and do us both some good. THEODORUS: I won't argue any further — lead on wherever you like. In any case, whatever fate you spin for me in this business, I must endure being tested by it. Only I won't be able to offer myself to you beyond what you've already proposed. SOCRATES: Even this much will be enough. And please watch closely for this: that we don't somehow slip into a childish kind of argument without noticing, and someone reproach us for it again. THEODORUS: Well, I'll try, as far as I'm able. SOCRATES: Then let's take up again the same point we did before, and see whether we were right or wrong to be unhappy and find fault with the argument for making each person self-sufficient in wisdom — and Protagoras conceded to us that some people surpass others regarding better and worse, and that these are the ones who are wise. Isn't that so? THEODORUS: Yes. SOCRATES: Now if he himself were here to agree to it, rather than us conceding it on his behalf in his defense, there would be no need to take it up again and secure it. But as things stand, someone might well say we have no authority to make that concession on his behalf. So it's better to come to a clearer agreement about this very point ourselves — for it makes no small difference whether it is so or not. THEODORUS: True.

SOCRATES: Then let's not get our agreement from other quarters, but from his own argument, in the shortest way possible. THEODORUS: How? SOCRATES: Like this: he says that whatever seems so to each person, is so for the one to whom it seems so? THEODORUS: Yes, that's what he says. SOCRATES: Well then, Protagoras, we too are speaking of the beliefs of a human being — or rather of all human beings — and we say there is no one who does not consider himself wiser than others in some respects, and others wiser than himself in other respects; and indeed in the greatest dangers, when men are hard pressed in wars or illness or storms at sea, they treat the leaders in each situation as if they were gods, expecting them to be their saviors, differing from the rest in nothing but knowledge. And the whole human world is full of people seeking teachers and rulers, for themselves and for other creatures and for their various trades, and believing in turn that some are competent to teach and to rule, and others not. And in all this, what else can we say except that human beings themselves believe that wisdom and ignorance exist among them? THEODORUS: Nothing else. SOCRATES: And don't they consider wisdom to be true thinking, and ignorance false belief? THEODORUS: Of course. SOCRATES: Well then, Protagoras, what are we to do with the argument? Shall we say that human beings always judge truly, or sometimes truly and sometimes falsely? For from either answer, it follows that they don't always judge truly, but judge both ways. Consider, Theodorus, whether any follower of Protagoras — or you yourself — would be willing to fight to maintain that no one considers anyone else ignorant or holds false beliefs. THEODORUS: That's hard to believe, Socrates. SOCRATES: And yet the argument that man is the measure of all things is driven to exactly this conclusion. THEODORUS: How so? SOCRATES: Whenever you form a judgment about something in your own mind and declare it to me as your belief, then, according to his argument, this is true for you. But is it not possible for the rest of us to become judges of your judgment, or do we always judge that you believe truly? Or do countless people, every time, oppose you with contrary beliefs, thinking that you judge and believe falsely? THEODORUS: Yes, by Zeus, Socrates — countless indeed, as Homer says, are those who give me trouble from other people. SOCRATES: Well then? Do you want us to say that you at that moment believe truly for yourself, but falsely for the countless others? THEODORUS: It seems that must follow from the argument.

SOCRATES: And what about Protagoras himself? Isn't it necessary that, if neither he himself nor the majority of people believed that man is the measure — as indeed they don't — then this truth he wrote about would be true for no one at all? But if he himself believed it, while the majority don't share his opinion, then you realize that, first of all, to the extent that those who disagree outnumber those who agree, to that same extent it is more not the case than the case. THEODORUS: That must follow, if indeed it is to be and not to be depending on each individual belief. SOCRATES: And next comes the cleverest point of all: he concedes, about his own opinion, that the opinion of those who hold the opposite view — the view that he is wrong — is true, since he admits that everyone believes what is the case. THEODORUS: Certainly. SOCRATES: Then wouldn't he be conceding that his own view is false, if he admits that the view of those who consider him wrong is true? THEODORUS: Necessarily. SOCRATES: But the others, for their part, don't concede that they themselves are wrong, do they? THEODORUS: No, they don't. SOCRATES: And he, in turn, admits that this belief too is true, on the basis of what he has written. THEODORUS: Apparently. SOCRATES: So it will be disputed by everyone, starting with Protagoras himself — or rather, it will be conceded by him himself, whenever he grants that the person who says the opposite believes truly — at that point Protagoras himself will be conceding that not even a dog, nor any random human being, is the measure of anything he hasn't learned. Isn't that so? THEODORUS: So it seems. SOCRATES: Then, since it is disputed by everyone, Protagoras's 'Truth' would be true for no one — not for anyone else, and not even for the man himself. THEODORUS: We're running my friend down rather severely, Socrates. SOCRATES: But look, my friend, it isn't even clear that we're running past what's right. It stands to reason that, being older, he's wiser than we are; and if he could suddenly pop up out of the ground right here, up to the neck, he would very likely expose plenty of nonsense in me and, I'd guess, get agreement from you too — and then sink back down and go running off. But we, I think, have no choice but to make use of ourselves as we are, and to keep saying whatever seems true to us. And so now too, shall we say that anyone at all would agree to this much — that one person can be wiser than another, and also more ignorant? THEODORUS: That's certainly how it seems to me. SOCRATES: And would the argument best hold its ground at the point where we sketched it out in Protagoras's defense — that most things are, for each person, just as they seem to him: hot, dry, sweet, and everything of that sort. But if it's ever going to be conceded that one person differs from another in anything, it would be willing to grant this concerning what is healthy and what causes disease — that not every little woman or child, or even an animal, is capable of curing itself by knowing what is healthy for it, but that here, if anywhere, one person differs from another? THEODORUS: That's how it seems to me too.

SOCRATES: And the same holds for matters of the city — the fine and the shameful, the just and the unjust, the pious and the impious: whatever each city decides on and enacts as its own law, that is what's true for that city, and in these matters no private person is any wiser than another, nor is one city wiser than another. But when it comes to laying down what's advantageous or not advantageous for itself, there — if anywhere — he'll agree that one adviser really does differ from another, and one city's judgment from another's, as measured against the truth; he wouldn't dare to claim that whatever a city enacts as advantageous, believing it so, is bound to turn out advantageous. But in the other matter I mentioned — the just and unjust, the pious and impious — they're willing to insist that none of these has any fixed nature of its own, that whatever a community collectively decides becomes true the moment it's decided, and stays true for just as long as the decision stands. Even those who don't go the whole way with Protagoras's doctrine end up handling wisdom something like this. But look, Theodorus, one argument keeps overtaking us, a bigger one springing from a smaller. THEODORUS: Well, we've got the leisure for it, haven't we, Socrates? SOCRATES: So it seems. And in fact, my good man, I've often noticed before, and I notice again now, how natural it is that people who've spent a long time in philosophy look ridiculous when they show up in a courtroom as speakers. THEODORUS: What do you mean by that? SOCRATES: Those who've been dragged through courtrooms and the like since they were young, compared with those raised in philosophy and that sort of pursuit — I'd guess the first are like household slaves next to free men. THEODORUS: How so? SOCRATES: In this way: the philosophers always have what you just called leisure, and they carry on their discussions at their ease, in peace — just as we ourselves are now taking up a third topic in place of the last one — and so it is with them too, if whatever comes along pleases them more than the subject in hand, as has happened to us; and it makes no difference to them whether they speak long or short, so long as they hit on what's really so. But the others are always talking against the clock — the water clock keeps pressing them on — and they aren't free to make their speeches about whatever they'd like; their opponent stands over them under compulsion, with the sworn deposition being read out alongside, which they aren't allowed to stray from. Their speeches are always about a fellow slave, addressed to a master seated on the bench, holding some lawsuit in his hands; the contests are never for some abstract prize but always for the man's own stake, and often life itself is on the line. All this makes them tense and sharp, skilled at flattering the master with words and courting him with deeds — but small in soul, and crooked.

SOCRATES: Their growth, their straightness, their freedom — all this is stripped away by slavery from their youth, forcing them into crooked practices, throwing great dangers and fears onto souls still soft, burdens they can't bear along with justice and truth; so they turn at once to lying and to cheating one another in return, and get bent and twisted so many times over that they end up going from boys to men with nothing sound left in their minds, though they think themselves clever and wise. Well, that's the sort they are, Theodorus. Now do you want us to go through the men of our own chorus, or leave that be and turn back to the argument, so we don't overindulge — as we were just saying — in this freedom and hopping from one topic to another? THEODORUS: No, not at all, Socrates — go through them. You put it very well just now, that we who dance in this sort of chorus aren't servants of our arguments, but our arguments are like servants to us, and each one waits around to be finished off whenever we see fit; there's no judge standing over us, and no audience either, ready to find fault and set the rules, the way there is for poets. SOCRATES: Let's talk, then, it seems, since that's your pleasure, about the leaders among them — for what would anyone say about those who spend their time in philosophy only halfheartedly? These men, from their youth, don't even know the way to the marketplace, or where the courthouse is, or the council chamber, or any other public meeting place of the city; laws and decrees, spoken or written, they neither see nor hear; the scrambling of political clubs after office, their meetings, dinners, and revels with flute-girls — such things don't even occur to them in a dream. Whether someone in the city has turned out well or badly, or what trouble has come down to a man from his ancestors, on the father's side or the mother's, escapes him more thoroughly than, as they say, the pints of water in the sea. And he doesn't even know that he doesn't know all this — he doesn't hold back from it for the sake of reputation, but really and truly it's only his body that lies and dwells in the city, while his mind, judging all these things petty and worthless, disdains them utterly and takes wing, as Pindar says, to survey the earth from below and its flat surface, to chart the stars above the heavens, and to search out the whole nature of everything that is, in every direction, never lowering itself to anything close at hand.

THEODORUS: What do you mean by that, Socrates? SOCRATES: The same sort of thing happened to Thales, Theodorus — he was studying the stars, looking upward, and fell into a well, and they say a clever and pretty Thracian servant girl made fun of him, saying he was so eager to know what was up in the sky that he couldn't see what was in front of him, right at his feet. The same joke fits everyone who spends his life in philosophy. Truly, such a man doesn't notice his neighbor next door — not just what he's doing, but hardly even whether he's a man or some other creature. What a human being is, though, and what it belongs to such a nature to do or undergo that's different from anything else — that he searches after and goes to great trouble to work out. You follow me, Theodorus? Or not? THEODORUS: I do, and what you say is true. SOCRATES: So, my friend, when a man like this meets someone in private or in public — as I said at the start — if he's forced, in a courtroom or somewhere else, to talk about what's right at his feet and in front of his eyes, he gives the whole crowd something to laugh at, not just the Thracian girls, falling into wells and every kind of confusion out of sheer inexperience; his awkwardness is dreadful, and it makes him look like a fool. When it comes to insults, he has nothing of his own to throw at anyone, since he knows no evil of anyone, never having bothered to learn any; so, at a loss, he looks ridiculous. And when others sing their own praises and boast, his laughter is plainly not put on but genuine, and so he seems a simpleton. When he hears a tyrant or a king praised, he thinks he's hearing about one of the herdsmen — a swineherd, say, or a shepherd, or a cowherd — congratulated on how much he's managed to milk out of his flock; except he thinks such men have a harder and more treacherous animal to shepherd and milk, and that a man like that, penned in behind his walls up on some hill, is bound to grow just as coarse and uneducated as any herdsman, for want of leisure. And when he hears that someone owns ten thousand acres of land, or even more, and thinks that's an amazing amount to possess, it sounds to him like next to nothing, since he's used to taking in the whole earth at a glance.

SOCRATES: And when men chant their pedigrees — someone proud to point to seven wealthy grandfathers — he thinks their praise is altogether dull-eyed and short-sighted, since through lack of education they can't keep the whole picture in view, or work out that everyone has had countless thousands of grandfathers and ancestors before him, among whom rich and poor, kings and slaves, barbarians and Greeks, have turned up again and again for anyone you like. When people pride themselves on a roll of twenty-five ancestors and trace their line back to Heracles, son of Amphitryon, he finds the pettiness of it absurd — that they don't stop to reckon that the twenty-fifth ancestor back from Amphitryon was whatever chance made him, and so was the fiftieth before that — he laughs at their inability to do the arithmetic and shake off the puffed-up folly of an unreflective mind. In all these situations, then, such a man is laughed at by the crowd — partly because he seems arrogant, partly because he's ignorant of, and at a loss over, what's right in front of him. THEODORUS: What you describe is exactly how it happens, Socrates. SOCRATES: But then, my friend, when he himself pulls someone up out of that world, and gets him to leave behind questions like 'What wrong have I done you, or you me?' and turn instead to examining justice and injustice in themselves — what each of them is, and how they differ from everything else and from each other — or to leave behind 'Is a king happy?', 'Does he own piles of gold?', and turn to examining kingship and human happiness and misery generally, what sort of things they are, and in what way it belongs to a person by nature to attain the one and escape the other — when it's time for that small, sharp, litigious mind to give an account of all this, then it's his turn to return the joke: hung dizzy from the height, staring down bewildered from up there, unused to it, at a loss, stammering — he no longer gives the Thracian girls anything to laugh at, or any other uneducated person, since they don't even notice, but he gives it to everyone who's had the opposite upbringing from slaves. That, Theodorus, is the character of each: the one truly raised in freedom and leisure — the man you call a philosopher — who can't be blamed for seeming simple and useless when he's dropped into some menial task, not knowing how to pack up his own bedroll, say, or season a dish, or turn out flattering speeches; the other, who can handle all such tasks briskly and sharply, but doesn't know how to drape his cloak properly like a free man, or catch the true harmony of words to sing, as it should be sung, the truly happy life of gods and blessed men.

THEODORUS: If you could persuade everyone of what you're saying, Socrates, just as you've persuaded me, there'd be more peace and less evil among mankind. SOCRATES: But evil can't be destroyed, Theodorus — there must always be something opposed to the good — nor can it have its seat among the gods; it must, of necessity, haunt mortal nature and this region here below. That's why we should try to escape from here to there as quickly as we can. And escape means becoming like god so far as that's possible; and becoming like god means becoming just and pious, with understanding. But it's not at all easy, my excellent friend, to convince people that the reason most men give for avoiding wickedness and pursuing virtue — that one should practice the one and not the other for the sake of seeming good rather than bad — isn't the real reason. That, it seems to me, is just old wives' babble. Let's state the truth instead: god is in no way, in no respect, unjust, but as just as it's possible to be, and nothing is more like him than whichever of us becomes most just in turn. This is the true measure of a man's ability, and of his worthlessness and unmanliness. Knowing this is wisdom and true virtue; not knowing it is plain ignorance and vice. All the other so-called abilities and forms of cleverness, when found in political power, are vulgar, and in the arts, mechanical. So for the man who does wrong and speaks or acts impiously, by far the best course is not to grant that his wrongdoing makes him clever; such men glory in the reproach, thinking it means people take them for something other than fools, mere dead weight on the earth, but as the sort of men a city needs to survive. We should tell them the truth instead: precisely because they don't think themselves such, they are all the more truly such; for they're ignorant of the penalty of injustice, which is the one thing it's least excusable to be ignorant of. It isn't what they imagine — beatings and executions, which sometimes fall even on those who've done no wrong — but a penalty impossible to escape. THEODORUS: What penalty do you mean?

SOCRATES: Since there really are two patterns set up in the world, my friend—one divine and perfectly happy, the other godless and perfectly wretched—people don't see that this is so, and in their stupidity and utter thoughtlessness they don't even notice that through their unjust actions they're becoming like the one and unlike the other. And for this they pay a penalty: they go on living out the kind of life that resembles what they've become. If we tell them that unless they rid themselves of this cleverness of theirs, that place free of evils won't receive them even when they die, and that here on earth they'll go on forever having a life that matches the sort of person they are—bad people spending their time with other bad people—when they hear all this, being the clever, cunning men they are, they'll think it's just the ravings of fools. THEODORUS: Very much so, Socrates. SOCRATES: I know it, my friend. But there's one thing that happens to them: when it comes to a private conversation, when they have to give and take an account of the very things they condemn, and they're willing to hold out bravely for a good long while instead of running off like cowards, then—strange as it is, my good man—in the end they're not satisfied with their own arguments about these very things, and that famous rhetoric of theirs somehow withers away, so that it seems no better than a child's babbling. Well, since this is really a digression from our subject, let's drop it—otherwise more and more will keep pouring in and burying our original argument—and let's go back to where we were before, if that's all right with you. THEODORUS: For my part, Socrates, I don't find such things unpleasant to hear—they're easier to follow for someone my age. Still, if you think we should, let's return to the argument. SOCRATES: Well then, we were somewhere around the point where we said that those who claim reality is in flux, and that whatever seems true to each person is true for that person, are willing to insist on this most strongly in other matters, and not least concerning what is just—that whatever a city establishes as its considered judgment is indeed just for that city, for as long as it remains established. But when it comes to what is good, no one is brave enough anymore to maintain, in the same way, that whatever a city establishes as beneficial to itself, believing it to be so, is in fact beneficial for exactly as long as it's established as such—except perhaps someone quibbling over the mere name, which would really just be mockery of what we're discussing. Wouldn't it? THEODORUS: Certainly. SOCRATES: Let's not have him quibble over the name, then—let him look at the thing that's named. THEODORUS: Let's not, indeed. SOCRATES: Well, whatever name the city gives this thing, that's surely what it's aiming at when it makes law, and it establishes all its laws, so far as it can judge and manage, as the most beneficial to itself it can. Or is it looking toward something else when it legislates?

THEODORUS: Not at all. SOCRATES: And does it always hit the mark, or does each city often miss badly? THEODORUS: I should think it misses too. SOCRATES: There's a further point that would make everyone agree with this even more readily, if the question were asked about the whole class of things to which the beneficial belongs. That, I take it, has to do with future time as well. For whenever we legislate, we lay down our laws on the assumption that they'll be beneficial in time to come—and that's rightly called 'the future.' THEODORUS: Certainly. SOCRATES: Come, then, let's ask Protagoras—or anyone else who says the same things he does—this: 'Man is the measure of all things,' you say, Protagoras—of white, heavy, light, and everything of that sort. For having the standard for judging them in himself, he thinks things are the way he experiences them, and so he believes them to be true for himself, and real. Isn't that so? THEODORUS: It is. SOCRATES: Then does he also, we'll say, Protagoras, hold the standard within himself for things that are going to be—and does whatever he thinks will happen actually come about for the one who thought it? Take heat, for instance: when an ordinary person thinks he's coming down with a fever and that this heat is going to occur, while another person, a doctor, thinks the opposite—according to whose judgment should we say the future will turn out? Or according to both—so that for the doctor he'll turn out neither hot nor feverish, but for himself he'll be both? THEODORUS: That would be absurd. SOCRATES: No, I think when it comes to the sweetness or dryness a wine is going to have, it's the farmer's judgment that counts, not the lyre-player's. THEODORUS: Of course. SOCRATES: Nor, again, would a trainer judge better than a musician about whether something is going to be in tune or out of tune—something that will later seem well-tuned to the trainer himself. THEODORUS: Not at all. SOCRATES: So too, when a meal is being prepared, the judgment of someone who isn't a cook, about the pleasure it's going to give, is less authoritative than the cook's judgment, when that person is going to be the one dining. As for what's already pleasant to someone, or has already happened to be pleasant, let's not argue about that just yet—but as for what's going to seem pleasant, and going to be pleasant, to each person—is each person the best judge of that for himself, or would you, Protagoras, judge in advance, better than any layman, what argument is going to persuade each of us in a courtroom? THEODORUS: Indeed, Socrates, that's exactly what he claimed to be better at than anyone—that above all.

SOCRATES: Yes, by Zeus, my friend—otherwise no one would have paid him large sums of money to talk with him, if he hadn't persuaded the people around him that when it comes to what's going to happen and what's going to seem so, neither a prophet nor anyone else could judge better than the man himself. THEODORUS: Perfectly true. SOCRATES: And legislation, too, and the beneficial, concern the future—so wouldn't everyone agree that a city, in making its laws, is often bound to miss what's most beneficial? THEODORUS: Very much so. SOCRATES: Then we'll be speaking fairly to your teacher when we say that he's forced to admit that one man is wiser than another, and that such a man is the measure, while for me, who knows nothing, there's no necessity at all that I become the measure—as the argument on his behalf just now was forcing me to be, whether I wanted it or not. THEODORUS: That seems to me, Socrates, the point where the argument is most caught out—caught also in this, that it makes other people's opinions authoritative, and these opinions turned out to regard his own statements as not true at all. SOCRATES: In many other ways too, Theodorus, a claim like this—that every opinion of everyone is true—could be caught out. But regarding each person's present experience, from which perceptions and the opinions that go with them arise, it's harder to convict these of being untrue. Perhaps I'm talking nonsense, though—maybe they really are impregnable, and those who claim they're clear and count as knowledge may well be saying something true, and our friend Theaetetus here wasn't off the mark in identifying perception with knowledge. So we must come in closer, as the argument on Protagoras's behalf demands, and examine this reality-in-motion, tapping it to see whether it rings sound or cracked. There's been no small fight over it, and not a few fighters. THEODORUS: Far from small—in Ionia, in fact, it's spreading enormously. Heraclitus's followers champion this doctrine with great vigor. SOCRATES: All the more reason, my dear Theodorus, to examine it thoroughly, starting from the beginning, just as they themselves present it.

THEODORUS: By all means. And indeed, Socrates, concerning these followers of Heraclitus—or, as you put it, of Homer, and thinkers even older—the men themselves around Ephesus, who claim expertise in it, are no more possible to have a discussion with than madmen driven by a gadfly. They're literally swept along in accordance with their own writings; as for staying still on a point and an argument, and calmly answering and asking in turn—there's less of that in them than nothing at all. Rather, the sheer absence of any stillness in these men goes beyond 'nothing'—it's less than nothing. If you ask one of them something, he pulls out little riddling phrases from a quiver, as it were, and shoots them at you, and if you try to get an account of what he meant, you'll be struck by another one, freshly renamed. You'll never come to any conclusion with any of them—and they don't with each other either. They're very careful to let nothing stand firm, either in argument or in their own souls, believing—so it seems to me—that stability itself is the enemy. They wage relentless war on it and drive it out from everywhere, as far as they're able. SOCRATES: Perhaps, Theodorus, you've seen the men in combat and haven't kept company with them at peace—for they're not your friends. But I imagine they explain these things to their students at leisure, whomever they want to make like themselves. THEODORUS: What students, my good man? None of these people becomes anyone else's student—they spring up on their own, wherever each happens to catch the inspiration, and each thinks the other knows nothing. So from them, as I was about to say, you'd never get an account, willing or not—we have to take the problem up ourselves and examine it as if it were a puzzle set before us. SOCRATES: And that's a fair point. Well, this puzzle we've inherited—haven't we gotten it in one form from the ancients, who concealed their meaning from the many under the veil of poetry, saying that the origin of everything else, Ocean and Tethys, are flowing streams, and nothing stands still; and in another form from the more recent thinkers, who, being wiser, declare it openly, so that even the shoemakers among their audience can learn their wisdom by hearing it and stop foolishly believing that some things stand still while others move, and, learning instead that everything moves, honor them for it? But I nearly forgot, Theodorus, that others in turn have declared the opposite of all this—such as 'unmoving is the name for the whole,' and all the other things that Melissus and Parmenides maintain, in opposition to all these people, insisting that all things are one and it stands still, in itself, having no room in which to move.

SOCRATES: What, then, my friend, are we to do with all these people? For advancing little by little, we've found ourselves, without noticing, caught in the middle between both sides, and unless we somehow fight our way clear and escape, we'll pay the penalty—like those who play the line game in the wrestling schools, when they're grabbed by both sides and dragged in opposite directions. So it seems to me we should first examine the one group—the ones we set out after, those who say everything flows—and if they seem to be saying something sound, we'll pull ourselves over to their side, trying to escape the others; but if the partisans of the unmoving whole seem to speak more truly, we'll flee to them instead, away from those who set even the unmoving things in motion. And if both sides turn out to be saying nothing reasonable, we'll look ridiculous, thinking that we, mere nobodies, have something worth saying, while we've rejected men of great age and great wisdom. So consider, Theodorus, whether it's worth advancing into so great a danger. THEODORUS: It's quite unbearable, Socrates, not to examine what each of these two schools of men is saying. SOCRATES: Examine it we must, then, since you're so eager. It seems to me the starting point of the inquiry should be about motion—what exactly they mean when they say all things move. I mean something like this: do they speak of it as a single kind, or, as it seems to me, as two? But don't let it seem so to me alone—join in with me, so that whatever happens to us in the process, we experience it together. Tell me: do you call it motion when something changes place from one place to another, or also when it spins in the same place? THEODORUS: I do. SOCRATES: Let that, then, be one kind. But when a thing stays in the same place yet grows old, or becomes black from white, or hard from soft, or undergoes some other alteration—isn't that worth calling a different kind of motion? THEODORUS: It seems to me it must be, yes. SOCRATES: So I call these two kinds of motion: alteration, and change of place. THEODORUS: Rightly said. SOCRATES: Having made this distinction, then, let's put the question to those who claim all things move, and ask: do you say everything moves in both ways—both changing place and altering—or does part of it move in both ways, and part in only one? THEODORUS: Well, by Zeus, I can't say—but I think they'd say both ways. SOCRATES: Because otherwise, my friend, things will appear to them both moving and standing still, and it will be no more correct to say that all things move than to say they stand still. THEODORUS: Very true.

SOCRATES: So since these things must move, and not-moving belongs to none of them, everything is always moving in every kind of motion. THEODORUS: It must be so. SOCRATES: Now look at this point with me. When we spoke of the coming-to-be of heat, or whiteness, or anything else, didn't we say something like this — that each of these travels, together with perception, in between the agent and the patient, and the patient becomes something that has the capacity to perceive, but is not yet a perception, while the agent becomes something of a certain quality, but is not yet a quality itself? Perhaps 'quality' sounds like a strange word all at once, and you don't follow it stated in one lump — so let me put it piece by piece. The agent is neither heat nor whiteness, but it becomes hot, or white, and so on with the rest. You'll remember from before that we said nothing is one thing by itself — not even the agent or the patient — but out of the two of them coming together with each other, perceptions and perceived things are born, the one becoming somehow qualified, the other becoming a perceiver. THEODORUS: I remember — of course. SOCRATES: Well then, let's leave the rest aside — whether they put it this way or that — and hold onto only the point for which we're saying this, and ask: are all things in motion and flux, as you people say? Isn't that so? THEODORUS: Yes. SOCRATES: And in both the kinds of motion we distinguished — moving-in-place and altering? THEODORUS: Of course — if it's really going to be complete motion. SOCRATES: Now if things merely moved in place without altering, we could say what sort of things these moving things are as they flow — or how else would we put it? THEODORUS: Just so. SOCRATES: But since not even this stays put — that the white thing flowing is white — but it changes, so that there is a flow of this very thing, whiteness, and a change into another color, so that it can never be caught staying put in that respect — can one ever call any color by name in a way that names it correctly? THEODORUS: How could one, Socrates? Or name anything else of that sort, if it's always slipping away as one speaks, being in flux as it is? SOCRATES: And what shall we say about any perception whatsoever — seeing, say, or hearing? Does it ever stay put in the very act of seeing or hearing? THEODORUS: It shouldn't, at least, if everything is in motion. SOCRATES: Then we shouldn't call it seeing any more than not-seeing, nor any other perception any more than not — given that everything, in every way, is in motion. THEODORUS: No, we shouldn't. SOCRATES: And yet perception is knowledge, as Theaetetus and I said. THEODORUS: That's what we said. SOCRATES: So when we were asked what knowledge is, we answered with something no more knowledge than not-knowledge.

THEODORUS: So it seems. SOCRATES: It would be a fine correction to our answer, after all our eagerness to prove that everything moves, just so that answer would turn out right! But instead, it seems, what's come to light is that, if everything moves, every answer, on whatever subject one answers, is equally correct — one can say it is so, and equally that it is not so, or, if you like, that it comes to be so, so as not to pin the movers down with our own words. THEODORUS: You're right. SOCRATES: Except, Theodorus, that I said 'so' and 'not so.' But one oughtn't even say 'so' — for then it would no longer be moving, this 'so' — nor 'not so' either, for that isn't motion. Rather, the people who hold this theory need to establish some other kind of language, since as things stand they have no words to fit their own position — unless perhaps 'not even so' suits them best, said without limit. THEODORUS: That's certainly the dialect most natural to them. SOCRATES: Well then, Theodorus, we're rid of your friend, and we're still not conceding to him that every man is the measure of all things, unless he's a man of good sense; nor will we concede that knowledge is perception — at least not by the method that has everything in motion — unless our friend Theaetetus has some other way of putting it. THEODORUS: Excellently said, Socrates — for once this business is settled, I too was supposed to be released from answering you, according to our agreement, once the argument about Protagoras reached its end. THEAETETUS: Not before, Theodorus, you and Socrates have gone through those who claim, on the contrary, that the whole stands still, just as you proposed a moment ago. THEODORUS: Young as you are, Theaetetus, are you teaching your elders to do wrong by breaking their agreements? Get ready instead to give Socrates an account of what's left. THEAETETUS: Yes, if he's willing. But I'd love nothing better than to hear about the things I'm asking about. THEODORUS: You're calling Socrates to a cavalry battle on open ground by inviting him into this discussion. Ask your questions, then, and you'll hear. SOCRATES: But I don't think, Theodorus, that on the matters Theaetetus is urging I'll do as he asks. THEODORUS: Why won't you?

SOCRATES: Melissus and the others who say the whole is one and at rest — I'm not too embarrassed to examine them, for fear of seeming crude, less embarrassed than I am about one man alone, Parmenides. Parmenides seems to me, in Homer's phrase, both an object of reverence and one to be feared. I met the man when I was quite young and he quite old, and he struck me as having a depth that was altogether noble. So I'm afraid we may not even grasp what was said, and fall far short of what he meant when he said it — and, worst of all, that the very question for whose sake the argument was set going — what knowledge actually is — may go unexamined, buried under all the arguments crashing in on us uninvited, if we let ourselves be swept along by them. Especially since the question we're now stirring up is itself immense — if one treats it as a side issue, it will get unworthy treatment, and if one treats it properly, being drawn out at length, it will bury the question of knowledge out of sight. Neither should happen. Instead we should try, using our art of midwifery, to deliver Theaetetus of what he's carrying about knowledge. THEODORUS: Well, if that's your judgment, that's what we should do. SOCRATES: Now then, Theaetetus, consider this further point about what's been said. You answered that knowledge is perception — right? THEAETETUS: Yes. SOCRATES: So if someone asked you this: 'By what does a person see white and black things, and by what does he hear high and low sounds?' you'd say, I imagine, 'By the eyes and the ears.' THEAETETUS: I would. SOCRATES: Being easy about words and phrases, and not scrutinizing them too closely, is usually not a mark of bad breeding — quite the opposite is rather ungenerous — but sometimes it's necessary, and this is one of those times when we have to take hold of the answer you gave, insofar as it isn't right. Consider: which answer is more correct — that the eyes are that by which we see, or that through which we see; and that the ears are that by which we hear, or that through which we hear? THEAETETUS: I think it's more correct to say we perceive through them rather than by them, Socrates. SOCRATES: Yes, for it would be strange, my boy, if a number of perceptions were sitting inside us as if in wooden horses, rather than all of them converging on some single form — call it soul, or whatever one should call it — by which, through these as instruments, so to speak, we perceive whatever is perceivable. THEAETETUS: Yes, that seems more likely to me than the other way. SOCRATES: The reason I'm being so precise about this is to find out whether it's by some one and the same thing in us that we reach whites and blacks through the eyes, and other things again through the other senses, and whether, if asked, you'll be able to refer all such cases back to the body. But perhaps it's better for you to answer and say these things yourself, rather than have me busy myself on your behalf. Tell me: hot and hard and light and sweet things, which you perceive through the body — don't you assign each of them to the body? Or to something else? THEAETETUS: To nothing else.

SOCRATES: And will you also be willing to agree that what you perceive through one faculty, it's impossible to perceive through another — what you perceive through hearing, say, through sight, or what you perceive through sight, through hearing? THEAETETUS: Of course I'll agree to that. SOCRATES: So if you have some thought about both of them together, you couldn't be perceiving something common to both through either one of the two organs alone. THEAETETUS: No, indeed. SOCRATES: Now take sound and color. First, do you think this very thing about both of them — that they both exist? THEAETETUS: I do. SOCRATES: And also that each is different from the other, but the same as itself? THEAETETUS: Of course. SOCRATES: And that the two together are two, and each one is one? THEAETETUS: That too. SOCRATES: And are you also able to consider whether the two are unlike each other or alike? THEAETETUS: Perhaps. SOCRATES: Now through what do you think all these things about the pair? Neither through hearing nor through sight can one grasp what's common to them. Here's further evidence for what we're saying: if it were possible to examine whether the two of them are salty or not, you know you'd be able to say by what you'd examine it, and it plainly isn't sight or hearing, but something else. THEAETETUS: Of course — the power that works through the tongue. SOCRATES: Well put. But through what does the power work that reveals to you what's common to all things, including these — the very thing you're naming when you say 'is' and 'is not,' and the other things we were just now asking about them? What organs will you assign for all these, through which the perceiving part of us perceives each of them? THEAETETUS: You mean being and not-being, and likeness and unlikeness, and sameness and difference, and also oneness and numbers in general as applied to them. And clearly you're also asking through what bodily organ we perceive, with the soul, even and odd, and everything else that goes along with these. SOCRATES: You're following superbly, Theaetetus, and these are exactly the things I'm asking about. THEAETETUS: But by Zeus, Socrates, I couldn't say — except that it seems to me there's no special organ at all for these, the way there is for those other things; rather the soul itself, through itself, seems to me to survey what's common to everything. SOCRATES: You're a handsome man, Theaetetus, and not, as Theodorus said, ugly — for whoever speaks handsomely is both handsome and good. And besides being handsome, you've done me a great favor by freeing me from a very long argument, if it appears to you that the soul examines some things by itself, through itself, and others through the powers of the body. For that was exactly what I myself thought, and I wanted you to think it too.

THEAETETUS: Well, it certainly does appear that way. SOCRATES: To which class, then, do you assign being? For that above all attaches to everything. THEAETETUS: I'd put it among the things the soul itself reaches for by itself. SOCRATES: And likeness too, and unlikeness, and sameness and difference? THEAETETUS: Yes. SOCRATES: What about the beautiful and the ugly, the good and the bad? THEAETETUS: These too, it seems to me, are among the things whose being the soul examines most of all by comparing them with each other, reckoning within itself things past and present against things to come. SOCRATES: Hold on. Won't it perceive the hardness of something hard through touch, and likewise the softness of something soft? THEAETETUS: Yes. SOCRATES: But their being, and that they both exist, and their opposition to each other, and again the being of that opposition — these the soul itself tries to determine for us by going back over them and comparing them with one another. THEAETETUS: Certainly. SOCRATES: So some things are there for humans and animals alike to perceive by nature, the moment they're born — whatever experiences reach the soul through the body — while the reckonings about these, concerning their being and their usefulness, come only with difficulty and over time, through much trouble and education, to those to whom they come at all? THEAETETUS: Absolutely. SOCRATES: Is it possible, then, to attain truth where one doesn't even attain being? THEAETETUS: Impossible. SOCRATES: And will someone who misses the truth of a thing ever have knowledge of it? THEAETETUS: How could he, Socrates? SOCRATES: Then knowledge lies not in the experiences themselves, but in the reasoning about them — for it's there, it seems, that one can grasp being and truth, but not there, in the experiences. THEAETETUS: So it appears. SOCRATES: Do you really call those two the same thing, then, when they differ so greatly? THEAETETUS: That certainly wouldn't be right. SOCRATES: Then what name do you give to the other one — seeing, hearing, smelling, feeling cold, feeling hot? THEAETETUS: Perceiving — what else would I call it? SOCRATES: So you call the whole of it, together, perception? THEAETETUS: It must be so. SOCRATES: Something, we're saying, that has no share in reaching truth — since it has none in reaching being. THEAETETUS: No, it doesn't. SOCRATES: Nor, then, in knowledge. THEAETETUS: No. SOCRATES: Then perception and knowledge, Theaetetus, could never be the same thing. THEAETETUS: It doesn't look like it, Socrates. And now, more than ever, it's become perfectly clear that knowledge is something other than perception.

SOCRATES: But surely this was never the point of our conversation—to find what knowledge is not, but what it is. Still, we've made this much progress: we no longer look for it in perception at all, but in whatever it is the soul is called when it goes to work by itself on the things that are. THEAETETUS: But surely that's called forming a judgment, Socrates, or so I think. SOCRATES: You think rightly, my friend. Now look again from the beginning, wiping away everything said before, and see whether you can see more clearly now that you've come this far. Tell me again what knowledge is. THEAETETUS: It's impossible to say it's judgment in general, Socrates, since judgment can also be false. But true judgment is probably knowledge, and let that be my answer. If it doesn't hold up as we go further, as it's holding up right now, we'll try to say something else. SOCRATES: That's the spirit, Theaetetus—better to answer boldly than to hesitate the way you did at first. If we go on like this, one of two things will happen: either we'll find what we're after, or we'll be less inclined to think we know what we don't know at all—and that would be no shabby reward. So tell me now: there being two kinds of judgment, one true and the other false, do you define knowledge as the true judgment? THEAETETUS: I do—that's how it looks to me now. SOCRATES: Then is it still worth going back over judgment— THEAETETUS: Which part do you mean? SOCRATES: Something has been troubling me, now and many times before, so that I've been at a total loss with myself and with others, unable to say what this experience is in us and how it comes about. THEAETETUS: Which experience? SOCRATES: Judging something falsely. I'm looking at it right now, still uncertain whether we should leave it be or examine it some other way than we just did. THEAETETUS: Why not, Socrates, if it really seems necessary? Just now you and Theodorus were saying, quite rightly, that in matters like these there's no need to rush. SOCRATES: A fair reminder—perhaps it isn't a bad time to pick up the trail again. Better to finish a small thing well than a large one inadequately. THEAETETUS: Quite so. SOCRATES: Well then, what exactly are we saying? We say that judgment is sometimes false, and that one of us judges falsely while another judges truly, as though that were simply how things are by nature? THEAETETUS: Yes, that's what we say.

SOCRATES: Now isn't this true for us about everything, taken one by one: either we know it or we don't know it? I'll set aside learning and forgetting as things that happen in between—they're irrelevant to our argument right now. THEAETETUS: But surely, Socrates, nothing else is left concerning any given thing except knowing it or not knowing it. SOCRATES: Then isn't it already necessary that anyone who judges is judging about something he either knows or doesn't know? THEAETETUS: Necessary. SOCRATES: And it's impossible for someone who knows a thing not to know that very thing, or for someone who doesn't know it to know it. THEAETETUS: Of course. SOCRATES: So does the person who judges falsely take things he knows and think they're not those things but some other things he knows—so that, knowing both, he's somehow ignorant of both at once? THEAETETUS: That's impossible, Socrates. SOCRATES: But perhaps he takes things he doesn't know to be other things he doesn't know—so that someone who knows neither Theaetetus nor Socrates could get it into his head that Socrates is Theaetetus, or Theaetetus is Socrates? THEAETETUS: How could he? SOCRATES: But surely no one takes things he knows to be things he doesn't know, nor things he doesn't know to be things he does know. THEAETETUS: That would be a monstrosity. SOCRATES: Then how could anyone still judge falsely? Outside these possibilities there's no way to judge at all, since everything falls under either knowing or not knowing, and within these it appears nowhere possible to judge falsely. THEAETETUS: Very true. SOCRATES: So shouldn't we look at what we're after not in terms of knowing and not knowing, but in terms of being and not being? THEAETETUS: What do you mean? SOCRATES: Maybe it's simply this: whoever judges what is not, about anything at all, cannot help but judge falsely, whatever state his mind happens to be in otherwise. THEAETETUS: That sounds likely too, Socrates. SOCRATES: Well then—what shall we say, Theaetetus, if someone presses us on this: is it possible for anyone, and will any human being ever judge what is not, whether about something that is or all by itself? And it seems we'll answer: yes, whenever he believes something untrue while believing it. Or how shall we put it? THEAETETUS: That way. SOCRATES: Does the same sort of thing happen anywhere else? THEAETETUS: Which sort? SOCRATES: If someone sees something, but sees nothing. THEAETETUS: How could that be? SOCRATES: But surely if he sees some one thing, he sees something that is. Or do you think the number one can ever belong among things that are not? THEAETETUS: I don't. SOCRATES: So whoever sees some one thing sees something that is. THEAETETUS: So it appears.

SOCRATES: And whoever hears something hears some one thing, and hears something that is. THEAETETUS: Yes. SOCRATES: And whoever touches something touches some one thing, and something that is, if indeed it's one thing? THEAETETUS: That too. SOCRATES: And doesn't whoever judges, judge some one thing? THEAETETUS: Necessarily. SOCRATES: And whoever judges some one thing judges something that is? THEAETETUS: I grant it. SOCRATES: So whoever judges what is not judges nothing. THEAETETUS: So it appears. SOCRATES: But surely whoever judges nothing isn't judging at all. THEAETETUS: That seems clear. SOCRATES: Then it's not possible to judge what is not, either about things that are or all by itself. THEAETETUS: It doesn't appear so. SOCRATES: Then judging falsely must be something different from judging things that are not. THEAETETUS: It seems different. SOCRATES: So neither this way nor the way we examined it a little earlier is false judgment present in us. THEAETETUS: No, it isn't. SOCRATES: But is this perhaps what we mean when we name it? THEAETETUS: How so? SOCRATES: We say false judgment is a kind of cross-judging—when someone, exchanging one thing that is for another thing that is, declares in his mind that it is that other thing. In this way he always judges something that is, but one thing instead of another, and since he misses the very thing he was aiming at, he could rightly be called someone judging falsely. THEAETETUS: Now you seem to me to have put it exactly right. When someone judges the ugly to be beautiful, or the beautiful to be ugly, that's truly judging falsely. SOCRATES: Clearly, Theaetetus, you're feeling bold with me rather than cautious. THEAETETUS: Why do you say that? SOCRATES: I don't think you'd let me get hold of true falsehood, if I asked whether it's possible for something quick to become slow, or something light to become heavy, in accordance with the nature of its opposite rather than its own—becoming, that is, the opposite of itself. Well, I'll let that go, so you don't get bold for nothing. But do you stand by this: that judging falsely is cross-judging? THEAETETUS: I do. SOCRATES: So on your view it's possible to set one thing down in the mind as another, and not as that very thing itself. THEAETETUS: It is indeed. SOCRATES: Then whenever someone's mind does this, isn't it necessary that it's thinking of both things, or one of them? THEAETETUS: Necessary—either both together, or one at a time. SOCRATES: Excellent. And do you mean by "thinking" what I mean? THEAETETUS: What do you mean by it?

SOCRATES: A discourse the soul carries on with itself about whatever it's examining. I'm telling you this as someone who doesn't really know, mind you. But this is how it appears to me: when the soul thinks, it's doing nothing but conversing—asking itself questions and answering them, affirming and denying. And when it has settled the matter, whether slowly or in a quick leap, and says the same thing at last without wavering, that's what we call its judgment. So for my part I call judging speaking, and judgment speech that has been spoken—not aloud to someone else, but silently to oneself. What about you? THEAETETUS: I agree. SOCRATES: So whenever someone judges one thing to be another, he's saying to himself, it seems, that the one thing is the other. THEAETETUS: Of course. SOCRATES: Try to recall, then, whether you've ever said to yourself that the beautiful is, in fact, ugly, or the unjust just. Or, to put the whole matter in one question: consider whether you've ever tried to convince yourself that one thing simply is another—or, on the contrary, whether even in a dream you've ever dared to say to yourself that odd numbers are, without qualification, even, or anything of that sort. THEAETETUS: What you say is true. SOCRATES: And do you think anyone else, sane or mad, would ever dare to tell himself in earnest, trying to persuade himself, that an ox must be a horse, or that two must be one? THEAETETUS: No, by Zeus, not I. SOCRATES: So if speaking to oneself is judging, then no one who says both things and judges both, grasping both in his soul, would say and judge that the one is the other. And you too must let go of that phrase "the other"—I mean by it that no one judges the ugly to be beautiful, or anything of that kind. THEAETETUS: Well, Socrates, I do let it go, and I think you're right. SOCRATES: Then someone thinking of both things at once can't possibly judge the one to be the other. THEAETETUS: So it seems. SOCRATES: But then again, someone thinking only of the one and not at all of the other will never judge the one to be the other either. THEAETETUS: True—for that would require him to grasp even what he isn't thinking of. SOCRATES: So neither thinking of both nor thinking of one alone leaves room for cross-judging. So if anyone means by false judgment this cross-judging, he's saying nothing—for false judgment turns out to be present in us neither this way nor in the way we examined before. THEAETETUS: It doesn't seem so. SOCRATES: And yet, Theaetetus, if this turns out not to exist, we'll be forced to admit a great many strange things. THEAETETUS: Such as what?

SOCRATES: I won't tell you until I've tried looking at it from every angle. I'd be ashamed on our behalf if, stuck as we are, we were forced to admit the sorts of things I have in mind. But if we find a way through and get free, then we can speak about others caught in that predicament, standing clear of the absurdity ourselves. But if we're stuck everywhere, then, humbled, I suppose we'll hand ourselves over to the argument to be trampled and used however it likes, the way seasick men are. So listen to how I still see a possible path through this inquiry. THEAETETUS: Just tell me. SOCRATES: I'll say we were wrong to agree, when we agreed that it's impossible for someone to judge things he doesn't know to be the very things he does know, and so be deceived. It's actually possible in a way. THEAETETUS: Do you mean what I suspected myself back when we first said it was like that—that sometimes I, knowing Socrates, but seeing someone else at a distance whom I don't know, thought he was the Socrates I know? Something like what you're describing does happen. SOCRATES: And didn't we back away from that idea because it made us, who knew things, not know them? THEAETETUS: Quite so. SOCRATES: Then let's not set it up that way, but this way—maybe it will agree with us on some point, maybe it will resist. But we're caught in a place where we must test the argument by turning it every way. So see whether there's anything in this: is it possible for someone who doesn't yet know a thing to come to learn it later? THEAETETUS: It is indeed. SOCRATES: And again, one thing after another? THEAETETUS: Why not? SOCRATES: Now suppose, just for the sake of argument, that there's a block of wax lodged in our souls—larger in one person, smaller in another, of purer wax in one, dirtier in another, harder in some, softer in others, and in some of just the right consistency. THEAETETUS: I'll suppose it. SOCRATES: Let's say it's a gift from Memory, mother of the Muses, and that whenever we want to remember something we've seen or heard or thought up ourselves, we hold this wax under our perceptions and thoughts and stamp them into it, the way we press the design of a signet ring. And whatever gets stamped, we remember and know as long as the image remains in it; but whatever gets wiped away, or can't be stamped in the first place, we've forgotten and don't know. THEAETETUS: Let it be so. SOCRATES: Now take someone who knows these things but is looking at something he sees or hears, and consider whether he might judge falsely in some such way as this. THEAETETUS: In what way, exactly? SOCRATES: By thinking that things he knows are, at one moment, things he knows, and at another, things he doesn't know. For we were wrong earlier to agree that this was impossible. THEAETETUS: And how do you put it now?

SOCRATES: We need to state the whole thing from the beginning by drawing distinctions: it's impossible for someone to take something he knows -- holding a record of it in his soul, but not perceiving it -- and believe it to be something else he knows, something for which he also holds an imprint, but which he isn't perceiving either. And again, it's impossible to believe that something he knows is something he doesn't know and has no seal of at all -- or that something he doesn't know is something else he doesn't know -- or that something he doesn't know is something he does know. And it's impossible to believe that something he's perceiving is something else he's perceiving; or that something he's perceiving is one of the things he isn't perceiving; or that something he isn't perceiving is one of the things he isn't perceiving; or that something he isn't perceiving is something he is perceiving. And further still -- and this is even more impossible than those, if that's even possible -- to believe that something he both knows and perceives, and for which he holds the mark that matches the perception, is something else that he also knows and perceives and for which he also holds a matching mark. And when someone holds the record correctly for both what he knows and what he perceives, it's impossible for him to believe that what he knows is something he perceives in a way that doesn't match; and it's impossible that what he doesn't know and doesn't perceive is what he doesn't know and doesn't perceive; and impossible that what he neither knows nor perceives is what he doesn't know; and impossible that what he neither knows nor perceives is what he doesn't perceive. All these cases are beyond the reach of anyone forming a false belief within them. So what's left is that if false belief can arise anywhere, it's among cases of this last sort. THEAETETUS: Which sort? Maybe I'll understand better if you give me an example -- right now I'm not following. SOCRATES: Among things a person knows, he believes them to be some other things that he knows and perceives; or things he doesn't know, but perceives; or, among things he knows and perceives, that they're other things he also knows and perceives. THEAETETUS: Now I'm even further behind than before. SOCRATES: Then listen to it the other way around. I know Theodorus, and I have a memory in myself of what he's like, and the same with Theaetetus. Now, don't I sometimes see them and sometimes not, sometimes touch them and sometimes not, sometimes hear them or otherwise perceive them, and at other times have no perception of you two at all, yet remember you no less and know you within myself? THEAETETUS: Absolutely. SOCRATES: So here's the first thing I want you to grasp from what I'm saying: it's possible not to be perceiving something one knows, and it's also possible to be perceiving it. THEAETETUS: True. SOCRATES: And with things one doesn't know, isn't it often possible neither to perceive them, and often possible only to perceive them? THEAETETUS: That's possible too.

SOCRATES: Now see if you follow a bit better now. Suppose Socrates knows Theodorus and Theaetetus, but sees neither of them, and has no other perception of them present to him -- he could never form the inner belief that Theaetetus is Theodorus. Am I saying something, or nothing? THEAETETUS: Yes, something true. SOCRATES: Well, that was the first of the cases I mentioned. THEAETETUS: It was. SOCRATES: Second, then: knowing one of you but not the other, and perceiving neither, I could never believe that the one I know is the one I don't know. THEAETETUS: Right. SOCRATES: And third: knowing neither of you and perceiving neither, I couldn't believe that the one I don't know is some other one I don't know. And take it that you've heard again, in order, all the earlier cases -- in none of them will I ever form a false belief about you and Theodorus, whether I know both of you or am ignorant of both, or know one and not the other; and the same holds for perceptions, if you're following. THEAETETUS: I'm following. SOCRATES: So what's left is for false belief to occur in this case: when I know both you and Theodorus, and hold, in that block of wax, the marks of both of you like the impressions of signet rings, but seeing you both from far off and not clearly enough, I try to assign each mark to its proper appearance, fitting it into its own track so that recognition happens -- and then I miss, and, like people putting shoes on the wrong feet, I cross the marks and apply each person's appearance to the mark that belongs to the other; or the way sight behaves in mirrors, when right flows over to left, I suffer the same sort of thing and go wrong. It's then that the crossing of beliefs happens, and false believing. THEAETETUS: Yes, it does seem so, Socrates. It's remarkable how you describe what happens with belief. SOCRATES: And further, when I know both of you, and I'm perceiving one of you along with knowing him, but not the other, and my knowledge of that other one doesn't match his perception -- this is what I meant earlier, and you didn't follow me then. THEAETETUS: No, I didn't. SOCRATES: What I meant was this: when I know one of you and perceive him, and my knowledge of him matches the perception, I'll never believe he's some other person whom I both know and perceive, and for whom my knowledge in turn matches the perception. Wasn't that it? THEAETETUS: Yes.

SOCRATES: What was left out, though, is the case we're speaking of now -- the one where we say false belief arises: knowing both and seeing both, or having some other perception of both, but not holding each mark matched to its own perception -- rather like an unskilled archer who lets fly and misses the mark wide, going astray. And that, indeed, is exactly what has been named falsehood. THEAETETUS: With good reason. SOCRATES: And also when perception of the marks is present to one of them but not the other, and the mind fits the missing perception onto the one that's present -- in every such case the mind goes false. In short, about things a person neither knows nor has ever perceived, it seems there can be no falsehood and no false belief at all, if what we're saying now is sound; but about things we do know and perceive, it's right there, in those very things, that belief turns and twists, becoming false or true -- true when it draws together the matching impressions and imprints straight on and directly, false when it goes off at a slant, askew. THEAETETUS: Isn't that well put, Socrates? SOCRATES: You'll say so even more once you hear this too. Believing what's true is admirable, and being deceived is shameful. THEAETETUS: Of course. SOCRATES: Well, they say this is where it comes from. When the wax in someone's soul is deep and plentiful and smooth and worked to just the right softness, then the things that come in through the senses, stamped onto this heart of the soul -- as Homer called it, hinting at its likeness to wax -- leave marks in it that are clear and have enough depth, so they last a long time. People like this are, first of all, quick learners, and then retentive; they don't shuffle the marks of their perceptions around, but form true beliefs. Since the marks are distinct and set out with plenty of room, such people quickly sort each one onto its own stamp -- the things we call the things that are -- and they're the ones called wise. Or don't you agree? THEAETETUS: Enormously so. SOCRATES: But when someone's heart is shaggy -- the very thing that all-wise poet praised -- or when the wax is impure and full of grime, or too moist or too hard, then those with moist wax are quick to learn but forgetful, while those with hard wax are the opposite. And those whose hearts are shaggy and rough, full of stony grit or clay or dung mixed in, get blurred impressions.

SOCRATES: Blurred too are those whose wax is hard, since there's no depth to it; and blurred also are those whose wax is moist, since the marks quickly run together and become faint. And if, on top of all this, the marks are piled on top of one another for lack of room, because someone's little soul is cramped, they're even more blurred than the others. All these people are the sort prone to false belief. For when they see or hear or think of something, they can't quickly assign each thing to its proper place; they're slow, and they misappropriate what belongs to others, and they see wrong, hear wrong, and think wrong about a great many things -- and these people, in turn, are called mistaken about the things that are, and ignorant. THEAETETUS: What you say couldn't be more right, Socrates. SOCRATES: So should we say that false beliefs exist in us? THEAETETUS: Very much so. SOCRATES: And true ones too? THEAETETUS: True ones too. SOCRATES: So now we think we've adequately agreed that both these kinds of belief certainly exist? THEAETETUS: Overwhelmingly so. SOCRATES: It really is a fearsome and unpleasant thing, Theaetetus, to be a man who talks too much, so it seems. THEAETETUS: What do you mean? Why say that? SOCRATES: I'm annoyed at my own slowness to learn, and, frankly, at my own long-windedness. What else would one call it, when a person drags arguments up and down because he's too sluggish to be persuaded, and can't tear himself away from any single argument? THEAETETUS: But why are you annoyed? SOCRATES: I'm not just annoyed -- I'm afraid of what I'll answer if someone asks me: 'So, Socrates, have you discovered false belief? That it exists neither within the perceptions in relation to each other, nor within the thoughts, but in the joining of perception to thought?' And I imagine I'll say yes, preening myself as if we'd discovered something fine. THEAETETUS: It seems to me, Socrates, that what's just been shown isn't shameful at all. SOCRATES: 'So,' he'll say, 'you mean that a person, thinking only of a man -- not seeing him -- would never believe him to be a horse, something he neither sees nor touches, but only thinks of, with no other perception of it at all?' I think that's what I'll say he means. THEAETETUS: And rightly so. SOCRATES: 'Well then,' he'll say, 'take the number eleven, when someone is merely thinking of it and nothing else -- couldn't he, by this same argument, believe that it's twelve, when twelve too is something he's only thinking of?' Come now, you answer. THEAETETUS: Well, I'll answer that someone who's seeing or touching eleven things might believe they're twelve, but as for the eleven he holds purely in thought, he could never form that belief about them.

SOCRATES: Well then -- do you think anyone has ever, within himself, taken five and seven -- and I don't mean setting out seven men and five men to consider, or anything like that, but five itself and seven itself, the very things we say are recorded as imprints in that wax block, things about which we say false belief is impossible -- has anyone among men ever actually examined these very things, asking himself how many they come to, and has one person said, believing them to be eleven, while another said twelve -- or do all people alike say and believe they come to twelve? THEAETETUS: No, by Zeus -- plenty of people say eleven. And if you take a larger number to examine, the error is even more likely. I take it you mean this to apply to any number whatsoever. SOCRATES: You're right to take it that way. And consider whether what happens then is anything other than believing that the very twelve in the wax block is eleven. THEAETETUS: It does seem so. SOCRATES: So doesn't this bring us back again to our earlier arguments? Whoever undergoes this takes something he knows to be some other thing that he in turn knows -- which we said was impossible, and it was precisely on this basis that we were forcing false belief not to exist, so that the same person wouldn't be compelled at once to know and not know the same things. THEAETETUS: Very true. SOCRATES: So we have to show that believing falsely is something other than a mismatch between thought and perception. For if that's what it were, we'd never be deceived within our thoughts themselves. But as things stand, either there's no such thing as false belief, or it's possible to not know something one knows. Which of these do you choose? THEAETETUS: You're offering me an impossible choice, Socrates. SOCRATES: And yet the argument does seem likely to rule out both at once. Still -- since we must be bold about everything -- what if we tried being shameless? THEAETETUS: How so? SOCRATES: By being willing to say what sort of thing knowing actually is. THEAETETUS: And what's shameless about that? SOCRATES: You don't seem to realize that this whole discussion of ours, from the start, has been a search for knowledge, on the grounds that we don't know what it is. THEAETETUS: I do realize it. SOCRATES: Then doesn't it seem shameless to declare what knowing is like when we don't yet know what knowledge is? But the truth is, Theaetetus, we've long since been thoroughly unable to converse in a clean way. Countless times we've said 'we recognize' and 'we don't recognize,' 'we know' and 'we don't know,' as if we understood each other while we're still ignorant of knowledge itself; and even now, if you like, in what we've just said, we've again made use of 'being ignorant' and 'understanding,' as if it were proper to use these words while we're deprived of knowledge. THEAETETUS: But then how will you carry on the discussion, Socrates, avoiding those words?

SOCRATES: No one, being who I am—though if that man skilled in refutation were here now, he'd say to steer clear of talk like this, and he'd scold us sharply for what I'm about to say. But since we're only ordinary men, do you want me to be bold and say what understanding is? It seems to me it might get us somewhere. THEAETETUS: Be bold then, by Zeus. You'll be forgiven plenty for not steering clear of it. SOCRATES: Have you heard what people nowadays say understanding is? THEAETETUS: Maybe—but I don't recall it just now. SOCRATES: They say it's a having of knowledge, I believe. THEAETETUS: True. SOCRATES: Let's shift the wording slightly, then, and say it's a possessing of knowledge. THEAETETUS: How would you say that differs from the other? SOCRATES: Maybe not at all—but hear what I think and judge along with me. THEAETETUS: As long as I'm able to. SOCRATES: Well, having doesn't seem to me the same thing as possessing. Take a cloak: if someone buys one and has it in his power but isn't wearing it, we'd say he doesn't have it, though we'd say he possesses it. THEAETETUS: Rightly put. SOCRATES: Now consider whether it's possible to possess knowledge in that way without having it—say, if a man caught wild birds, doves or something else, and built himself a dovecote at home to keep them in. We might say he has them in a sense at all times, since he's got them. Right? THEAETETUS: Yes. SOCRATES: But in another sense he has none of them at all—rather, a power over them has come to be his, now that he's brought them under his control inside an enclosure of his own: the power to take hold of and grasp any one he wants, whenever he wants, catching whichever he chooses, and to let it go again, and to do this as often as he likes. THEAETETUS: That's so. SOCRATES: Once more, then, just as before we built some sort of waxen thing—whatever that odd device was—in people's souls, let's now make in each soul a kind of dovecote holding birds of every kind: some in flocks apart from the rest, some in small groups, others alone here and there, flying about the whole space however they happen to. THEAETETUS: All right, it's made. What comes next? SOCRATES: We should say that while we're children this container is empty, and instead of birds, think of pieces of knowledge; and whenever a man gets hold of some piece of knowledge and shuts it up inside the enclosure, we say he's learned or discovered the thing that knowledge is of—and that this is what understanding is. THEAETETUS: Let's grant it.

SOCRATES: Now consider what words are needed for going back and catching whichever piece of knowledge he wants, taking hold of it and having it, and then letting it go again—whether the same words as when he first acquired it, or different ones. You'll see more clearly what I mean from this: you speak of an art of arithmetic? THEAETETUS: Yes. SOCRATES: Take that to be a hunt for pieces of knowledge of everything even and odd. THEAETETUS: I take it so. SOCRATES: By means of this art, I think, a man both has the pieces of knowledge of numbers under his own control and hands them over to another when he teaches. THEAETETUS: Yes. SOCRATES: And we call the one handing them over a teacher, the one receiving them a learner, and the one who has them by possessing them in that dovecote, one who understands. THEAETETUS: Absolutely. SOCRATES: Now pay attention to what follows from this. A man who's a complete arithmetician—does he understand all numbers in some other sense? For he has within his soul pieces of knowledge of all numbers. THEAETETUS: Of course. SOCRATES: Could such a man, then, ever count anything—either the numbers themselves to himself, or some external thing that has a number? THEAETETUS: Of course he could. SOCRATES: But we'll take counting to be nothing other than examining how great some given number happens to be. THEAETETUS: That's so. SOCRATES: So it turns out that what he understands, he appears, in examining it, not to know—this very thing we agreed he knows as every number there is. You've heard such puzzles raised, I suppose. THEAETETUS: I have. SOCRATES: Well then, drawing our comparison from the acquiring and hunting of doves, we'll say the hunt was of two kinds: one before possessing them, for the sake of possessing them; the other, once possessed, for the sake of taking hold of and having in one's hands what one had possessed all along. In the same way, things a man already had pieces of knowledge of long ago, and knew, can be learned over again by taking up and grasping the knowledge of each of them anew—knowledge he'd possessed for a long time but didn't have ready at hand in his mind. THEAETETUS: True. SOCRATES: This is just what I was asking a moment ago—what words one ought to use in speaking of these things, when the arithmetician sets out to count, or the grammarian to read something: does he, though he understands, go again as one who will learn from himself what he already understands? THEAETETUS: But that's absurd, Socrates.

SOCRATES: Well then, shall we say instead that he'll read and count things he doesn't understand, granting that he understands every letter and every number? THEAETETUS: But that too is unreasonable. SOCRATES: Do you want us to say, then, that we don't care at all about the words—whichever way someone likes to stretch 'understand' and 'learn'—but since we've drawn a distinction between possessing knowledge and having it, we say it's impossible not to possess what one has acquired, so that it never happens that a man doesn't know what he knows, though it is possible for him to get a false judgment about it? THEAETETUS: SOCRATES: For it's possible for him not to have that piece of knowledge, but another instead of it—whenever, in hunting for some piece of knowledge among those flying about, he misses and grabs one instead of another, and then he thinks eleven is twelve, having taken hold of the knowledge of eleven instead of that of twelve, the one inside himself, as it were a wood-pigeon instead of a dove. THEAETETUS: Well, that makes sense. SOCRATES: But when he grabs the one he's trying to grab, then he isn't deceived and judges the things that are, and so there is both true and false judgment, and none of the things that troubled us before stands in the way any longer? Perhaps you'll agree with me—or how will you take it? THEAETETUS: That way. SOCRATES: Yes, for we've gotten rid of the problem of a man not understanding what he understands—since it no longer happens anywhere that we fail to possess what we've possessed, whether we've been deceived about something or not. Still, another and more troubling difficulty seems to me to be showing itself. THEAETETUS: Which one? SOCRATES: If the exchange of pieces of knowledge for one another should ever turn out to be a false judgment. THEAETETUS: How do you mean? SOCRATES: First, that a man who has knowledge of something should be ignorant of that very thing—not through lack of understanding, but by means of his own knowledge; and then that he should judge this thing to be that other thing, and that other thing to be this one—isn't it a great absurdity that, when knowledge is present, the soul should know nothing and be ignorant of everything? By this reasoning nothing prevents ignorance, when present, from making someone know something, and blindness from making someone see—if indeed knowledge is going to make someone ignorant of something at some point. THEAETETUS: Perhaps, Socrates, we didn't set up the birds well by putting only pieces of knowledge among them—we should also have put pieces of ignorance flying about together with them in the soul, and had the hunter sometimes catching a piece of knowledge, sometimes a piece of ignorance about the same thing, judging falsely by means of the ignorance and truly by means of the knowledge.

SOCRATES: It's not easy, Theaetetus, not to praise you—but look again at what you just said. Let it be as you say: the man who's caught the ignorance, you say, will judge falsely. Right? THEAETETUS: Yes. SOCRATES: But surely he won't also think that he's judging falsely. THEAETETUS: How could he? SOCRATES: No, he'll think he's judging truly, and he'll be disposed as one who knows regarding the very things about which he's been deceived. THEAETETUS: Of course. SOCRATES: So he'll suppose he has, by his hunting, knowledge—not ignorance. THEAETETUS: Clearly. SOCRATES: So, after going a long way round, we're back again at the very first difficulty. That man skilled in refutation will laugh and say: Best of men, does someone who knows both of them—knowledge and ignorance—suppose that one of them, which he knows, is some other one of the things he knows? Or, knowing neither of them, does he suppose that one thing he doesn't know is some other thing he doesn't know? Or, knowing one but not the other, does he suppose the one he knows is the one he doesn't know? Or the one he doesn't know is the one he knows? Or will you tell me again that of the pieces of knowledge and ignorance there are in turn further pieces of knowledge, which their possessor has shut up in some other ridiculous dovecotes or waxen molds, and understands as long as he possesses them, even if he doesn't have them ready at hand in his soul—and so you'll be forced to run round and round to the very same point, over and over, getting nowhere? What shall we answer to this, Theaetetus? THEAETETUS: But, by Zeus, Socrates, I really don't know what to say. SOCRATES: Then is the argument right, my boy, to rebuke us and to show that we're wrong to look for false judgment before understanding, setting the latter aside? It's impossible to know the one until someone has adequately grasped what understanding itself is. THEAETETUS: As things stand, Socrates, one has to think as you say. SOCRATES: Well then, what will someone say understanding is, starting over again from the beginning? For surely we're not going to give up just yet? THEAETETUS: Not at all, unless you yourself give up. SOCRATES: Tell me, then, what could we say it is that would least contradict ourselves? THEAETETUS: What we were trying before, Socrates—I have nothing else to offer. SOCRATES: What was that? THEAETETUS: That true judgment is understanding. Judging truly is surely free of error, and everything that comes of it turns out fine and good.

SOCRATES: The man leading the way across the river, Theaetetus, said he'd show it to us. And if we go on and search this out, maybe the thing itself, in getting in our way, will reveal what we're looking for—whereas if we stand still, nothing will become clear. THEAETETUS: You're right—let's go on and look. SOCRATES: Well, this much at least needs little examination: a whole art shows you that this can't be understanding. THEAETETUS: How so? Which art? SOCRATES: The art of those reckoned greatest in wisdom, the ones called orators and pleaders in the courts. These men, by their own art, persuade people not by teaching them but by making them judge whatever they want them to judge. Or do you think there are teachers so clever that, for people who weren't present to see money being stolen from someone, or some other act of violence, they can teach the truth of what happened well enough in the short time allowed at the water-clock? THEAETETUS: Not at all, I think—only persuade them. SOCRATES: And by persuading, you mean making them judge something? THEAETETUS: Of course. SOCRATES: So whenever jurors are rightly persuaded about matters that can only be known by having seen them, and not otherwise, and in judging these from hearsay they arrive at a true judgment, they've judged without understanding, even if they've been rightly persuaded, granted that they judged well? THEAETETUS: Quite so. SOCRATES: But, my friend, if true judgment and understanding were the same thing, not even the finest juror would ever judge rightly without understanding. As it is, it seems the two are different things. THEAETETUS: There's something, Socrates, that I heard someone say once and had forgotten, but I recall it now: he said that true judgment together with an account is understanding, while true judgment without an account falls outside understanding; and things of which there is no account are not objects of understanding—calling them that—while those that have one are objects of understanding. SOCRATES: Well said. But tell me how he divided up these objects of understanding, and those that aren't, so we can see whether you and I have heard the same account. THEAETETUS: But I'm not sure I can work it out—though if someone else told it, I think I could follow along. SOCRATES: Listen, then, to a dream in exchange for a dream. I too seemed to hear from certain people that the primary things, so to speak—elements out of which we and everything else are composed—admit of no account.

SOCRATES: Each thing by itself, on this view, could only be named — nothing further could be said of it, neither that it is nor that it is not. To say that would already be to attach being or non-being to it, and nothing at all must be added, if one is going to speak of that thing alone. Indeed not even the words "itself," "that," "each," "alone," or "this" may be added, nor many other such words — for these go running around attaching themselves to everything, and are different from the things to which they are attached. Whereas if it were possible to state the thing itself, and it had an account proper to it, it would have to be stated apart from all the others. But as things stand it is impossible for any of the primary elements to be expressed in an account at all — for it has nothing but a name; that is all it has. But the things composed out of these elements — just as the elements themselves are woven together, so their names, woven together, become a statement. For the essence of a statement, on this view, is the weaving-together of names. So it turns out that the elements are without account and unknowable, though perceivable, while the syllables are knowable and expressible and can be grasped by true judgment. So then, when someone grasps the true judgment about something without an account, his soul is in a state of truth about it, but he does not know it — for whoever cannot give and receive an account of a thing has no knowledge of it. But once he has acquired an account, he becomes capable of all this and is fully equipped for knowledge. Is this the dream as you heard it, or something else? THEAETETUS: Exactly this, in every respect. SOCRATES: Are you satisfied, then, and do you hold to this, that knowledge is true judgment joined with an account? THEAETETUS: I certainly am. SOCRATES: Can it be, Theaetetus, that today, on this very day, we have laid hold of something that many wise men before us went gray searching for and never found? THEAETETUS: At any rate it seems to me, Socrates, that what has just been said is well put. SOCRATES: And it is likely that this very point is so — for what could knowledge even be, apart from an account and correct judgment? Yet there is one thing in what has been said that does not sit well with me. THEAETETUS: What is that? SOCRATES: The very point that seems to be put most cleverly — that the elements are unknowable while the class of syllables is knowable. THEAETETUS: And isn't that right? SOCRATES: We must find out. We have, after all, hostages for this account — the examples the man used when he said all this. THEAETETUS: What examples? SOCRATES: The elements and syllables of the alphabet. Or do you think the one who said what we're describing had his eye on anything else when he said it? THEAETETUS: No, on exactly this.

SOCRATES: Let us test them, then, by going back over them — or rather, let us test ourselves, on whether this is or is not how we learned our letters. Consider first: do the syllables have an account, while the elements are without account? THEAETETUS: Perhaps. SOCRATES: That is certainly how it strikes me too. At any rate, if someone were asked about the first syllable of "Socrates" — Theaetetus, tell me, what is SO? — what would you answer? THEAETETUS: That it is sigma and omega. SOCRATES: And that is the account you have of the syllable? THEAETETUS: It is. SOCRATES: Come then, give the account of the sigma in the same way. THEAETETUS: But how could anyone state the elements of an element? Indeed, Socrates, the sigma is one of the voiceless letters, a mere noise, like the tongue hissing; and beta again has neither tone nor noise, nor do most of the letters. So it fits very well to say they are without account — seeing that even the clearest of them, the seven vowels, have only sound, and no account whatsoever. SOCRATES: On this point, then, my friend, we have got it right about knowledge. THEAETETUS: So it seems. SOCRATES: But what about this — that the element is unknowable while the syllable is knowable — have we shown that correctly? THEAETETUS: It seems likely. SOCRATES: Come then, when we speak of the syllable, do we mean both elements — and if there are more than two, all of them — or some single form that has come to be once they are put together? THEAETETUS: I think we mean all of them together. SOCRATES: Look at it with two: sigma and omega. Both together are the first syllable of my name. Whoever knows it knows both, doesn't he? THEAETETUS: Of course. SOCRATES: So he knows the sigma and the omega. THEAETETUS: Yes. SOCRATES: Well then — does he know each separately while being ignorant of both, and know both while knowing neither? THEAETETUS: But that would be strange and unreasonable, Socrates. SOCRATES: And yet if it is necessary to know each, given that one is going to know both, then it is absolutely necessary for anyone who is ever going to know a syllable to know the elements beforehand — and so our fine account will have run off and escaped us. THEAETETUS: Yes, and very suddenly too. SOCRATES: That's because we are not guarding it well. Perhaps we should have said that the syllable is not the elements, but some single form that has come to be out of them — a single character of its own, distinct from the elements. THEAETETUS: Quite so — and perhaps that is closer to the truth than the other way. SOCRATES: We must examine this and not betray so unmanfully so grand and solemn an account. THEAETETUS: No, we must not.

SOCRATES: Let it stand, then, as we are now saying: the syllable is a single form arising from each set of fitted-together elements, alike in letters and in everything else. THEAETETUS: Quite so. SOCRATES: Then it must have no parts. THEAETETUS: Why is that? SOCRATES: Because wherever there are parts, the whole must necessarily be all the parts. Or do you also say that the whole, made up of the parts, is some single form distinct from all the parts? THEAETETUS: I do. SOCRATES: And do you call "the all" and "the whole" the same thing, or each different? THEAETETUS: I have nothing clear to say — but since you tell me to answer boldly, I'll take the risk and say they're different. SOCRATES: Your boldness, Theaetetus, is correct; whether your answer is too, we must examine. THEAETETUS: Yes, we must. SOCRATES: Then, by this present account, the whole would differ from the all? THEAETETUS: Yes. SOCRATES: Well now — do "all things" and "the all" differ at all? Take it this way: when we say one, two, three, four, five, six — and likewise if we say twice three, or three times two, or four and two, or three and two and one — are we in all these saying the same thing or something different? THEAETETUS: The same. SOCRATES: Namely six, and nothing else? THEAETETUS: Nothing else. SOCRATES: So in each way of saying it we have named all six? THEAETETUS: Yes. SOCRATES: And in saying "all things" do we name nothing at all? THEAETETUS: We must be naming something. SOCRATES: Nothing but the six? THEAETETUS: Nothing else. SOCRATES: So, at least among things made up of number, "the all" and "all things" name the same thing? THEAETETUS: So it appears. SOCRATES: Let us put it this way, then: the number belonging to a plot of land and the plot of land itself are the same, aren't they? THEAETETUS: Yes. SOCRATES: And likewise the number of a stade and the stade. THEAETETUS: Yes. SOCRATES: And indeed the number of an army and the army, and all such cases alike — for in each of them the whole number is the whole thing itself. THEAETETUS: Yes. SOCRATES: And the number belonging to each of these — is it anything other than its parts? THEAETETUS: Nothing else. SOCRATES: So whatever has parts would be made up of parts? THEAETETUS: It appears so. SOCRATES: And it has been agreed that all the parts are the whole, since the whole number too will be the whole thing. THEAETETUS: That's so. SOCRATES: Then the whole is not made up of parts — for if it were, being all the parts, it would be the all. THEAETETUS: It doesn't seem so. SOCRATES: And is a part a part of anything else at all except the whole? THEAETETUS: Yes, of the all, at least.

SOCRATES: You fight bravely indeed, Theaetetus. But when nothing is missing, isn't that very thing the all? THEAETETUS: It must be. SOCRATES: And won't this same thing be the whole — that from which nothing anywhere stands apart? Whereas whatever a thing stands apart from is neither whole nor all, since it has become, from the same cause, no longer the same thing? THEAETETUS: It seems to me now that "all" and "whole" differ in no way. SOCRATES: Well then, weren't we saying that wherever there are parts, the whole and the all will be all the parts? THEAETETUS: Quite so. SOCRATES: So again, as I was trying to say just now — isn't it necessary, if the syllable is not the elements, that it does not have the elements as its parts, or else, being the same as them, it would be equally knowable as they are? THEAETETUS: That's so. SOCRATES: And wasn't it to prevent that from happening that we made it something different from them? THEAETETUS: Yes. SOCRATES: Well then — if the elements are not parts of the syllable, can you name anything else that is a part of the syllable, but not one of its elements? THEAETETUS: Not at all. For if, Socrates, I were to grant it some parts of its own, it would be absurd to set aside the elements and go looking for other things. SOCRATES: So entirely then, Theaetetus, by the present account, a syllable would be some single form without parts. THEAETETUS: So it seems. SOCRATES: Do you remember, then, my friend, that a little earlier we accepted it, thinking it well said, that there is no account of the primary things out of which everything else is composed — because each of them, taken by itself, is uncompounded, and it isn't even right to speak of "being" concerning it, or even the word "this," as something said in addition and foreign to it — and that this very reason made it without account and unknowable? THEAETETUS: I remember. SOCRATES: Well, is there any other reason for its being single in form and without parts than this very one? I for one see none other. THEAETETUS: No, indeed, none appears. SOCRATES: Then the syllable has fallen into the same case as the element, if it truly has no parts and is a single form. THEAETETUS: Entirely so. SOCRATES: If, then, the syllable is many elements and some whole, and these are its parts, then the syllables are knowable and expressible just as much as the elements, since "all the parts" turned out to be the same as the whole. THEAETETUS: Quite true. SOCRATES: But if it is one thing, without parts, then the syllable is equally without account and unknowable as the element — for the same reasoning will make them both so. THEAETETUS: I can't say otherwise. SOCRATES: So we must not accept it, then, from anyone who says that the syllable is knowable and expressible, while the element is the opposite. THEAETETUS: No, we must not, if we are persuaded by the argument.

SOCRATES: But what again — wouldn't you rather welcome the opposite claim, judging from what you yourself know from learning your letters? THEAETETUS: What claim is that? SOCRATES: That in learning, you did nothing else but try to distinguish the elements, both by sight and by hearing, each one on its own, so that their order in speech and in writing wouldn't confuse you. THEAETETUS: What you say is perfectly true. SOCRATES: And in the music school, wasn't full mastery just this — being able to follow each note and tell which string it belonged to — the very things everyone would agree are the elements of music? THEAETETUS: Nothing else. SOCRATES: So then, going by the elements and syllables we ourselves have experience of, if we are to draw a conclusion from these to the rest, we would say that the class of elements affords a far clearer and more authoritative knowledge than the syllable does, for grasping any subject fully — and if anyone says that the syllable is knowable but the element unknowable by nature, we will take him to be joking, whether he means to or not. THEAETETUS: Quite so. SOCRATES: But other proofs of this could still be found, I think. Still, let us not lose sight, on account of these, of the question before us — namely, what in the world is meant by saying that knowledge is most complete when true judgment is joined by an account. THEAETETUS: Yes, we must look into that. SOCRATES: Come then, what can "the account" possibly mean for us? For it seems to me to be one of three things. THEAETETUS: Which three? SOCRATES: The first would be making one's own thought plain through speech, by means of verbs and nouns, imprinting one's judgment, as into a mirror or water, onto the stream that flows through the mouth. Doesn't something of that sort seem to you to be an account? THEAETETUS: It does to me. At any rate, we say that whoever does this is giving an account. SOCRATES: And isn't this, at least, something everyone is capable of doing, sooner or later — showing what he thinks about anything, unless he's been mute or deaf from birth? And so everyone who holds any correct judgment at all will turn out to have it along with an account, and correct judgment apart from knowledge will nowhere still occur. THEAETETUS: True.

SOCRATES: Let's not be too quick to convict the person who declared that knowledge is what we're now considering of saying nothing at all. Maybe what he meant wasn't that, but that when asked what any given thing is, one should be able to answer by breaking it down into its elements for the questioner. THEAETETUS: What sort of thing do you mean, Socrates? SOCRATES: The sort of thing Hesiod says about a wagon — that it has a hundred timbers. I couldn't list them, and I don't think you could either. We'd be satisfied, if asked what a wagon is, to be able to say: wheels, axle, body, rails, yoke. THEAETETUS: Quite so. SOCRATES: But he might think we were being ridiculous — the way someone would be ridiculous if asked to spell your name and answered letter by letter. We'd be forming a correct judgment and saying what we say correctly, but thinking we were being literate, and that we possessed and could state the literate account of the name "Theaetetus" — when in fact one can't speak with real knowledge about anything until one has gone through it element by element together with true judgment, as was said somewhere earlier. THEAETETUS: Yes, it was said. SOCRATES: So too with the wagon: we have a correct judgment about it, but the person who can go through its being by way of those hundred parts has, by adding this, added an account to true judgment, and has become, instead of someone with mere judgment, someone skilled and knowledgeable about the being of a wagon, by working through the whole via its elements. THEAETETUS: And doesn't that seem right to you, Socrates? SOCRATES: If it seems right to you, my friend, and you accept that going through something element by element is an account of it, while going through it by syllables, or anything coarser still, is no account at all — then tell me so, so we can examine it. THEAETETUS: I do accept it, entirely. SOCRATES: Do you think someone has knowledge of anything at all, when the same thing seems to him at one time to belong to one thing and at another time to another — or when he judges the same thing to be, at one time one thing and at another time something else? THEAETETUS: No, by Zeus, I don't. SOCRATES: Then have you forgotten how, when you were first learning your letters, you and everyone else behaved? THEAETETUS: Are you talking about how we'd take the same letter to be sometimes one thing and sometimes another, and would put the same letter now into the syllable it belonged in, and now into a different one? SOCRATES: That's what I mean. THEAETETUS: No, by Zeus, I haven't forgotten, and I certainly don't think people in that condition have knowledge yet.

SOCRATES: Well then — when someone in just that condition is writing "Theaetetus" and thinks he ought to write, and does write, theta and epsilon, and again, trying to write "Theodorus," thinks he ought to write, and does write, tau and epsilon — shall we say he knows the first syllable of your two names? THEAETETUS: But we just agreed that someone in that state doesn't yet know. SOCRATES: Is there anything to stop the same person from being in that condition regarding the second syllable, and the third, and the fourth? THEAETETUS: Nothing at all. SOCRATES: Then in that case, when he writes it in the correct order, does he write "Theaetetus" with the elemental breakdown plus correct judgment? THEAETETUS: Clearly so. SOCRATES: But still without knowledge, while judging correctly — as we're saying? THEAETETUS: Yes. SOCRATES: Yet having an account together with correct judgment. For he wrote it having the path through the elements, which we agreed was an account. THEAETETUS: True. SOCRATES: So, my friend, there is such a thing as correct judgment with an account, which we shouldn't yet call knowledge. THEAETETUS: It looks that way. SOCRATES: So it seems we were dreaming when we thought we'd struck the truest possible account of knowledge. Or should we hold off on that verdict? Perhaps this isn't what someone would use to define it, but rather the remaining one of the three kinds we said someone might propose — namely that knowledge is correct judgment together with an account. THEAETETUS: You're right to remind me — there is still one left. One was like an image of thought in speech; the one just mentioned was the path through the elements to the whole; but what do you mean by the third? SOCRATES: What most people would say — having some mark to state by which the thing in question differs from everything else. THEAETETUS: Can you give me an example of what account of what you mean? SOCRATES: For instance, take the sun — I think it's enough for you to accept that it's the brightest of the things that travel through the sky around the earth. THEAETETUS: Quite so. SOCRATES: Now grasp why I say this. It's what we were just saying: that if you grasp the way each thing differs from everything else, you'll get, as some say, an account of it; but as long as you're only touching on something common to it and other things, your account will apply to all the things that share that common feature. THEAETETUS: I understand — and it seems right to me to call that kind of thing an account. SOCRATES: And whoever adds, to correct judgment about any existing thing, its difference from everything else, will have become knowledgeable about the very thing he was previously only judging. THEAETETUS: Yes, that's what we're claiming. SOCRATES: But now, Theaetetus, now that I've come close, as it were, to the outline sketch of what's being said, I understand it not even a little — whereas as long as I stood back at a distance, it seemed to me that something was being said. THEAETETUS: How do you mean?

SOCRATES: I'll explain, if I can manage it. Suppose I have a correct judgment about you: if I add your account, then I know you; but if not, I merely judge. THEAETETUS: Yes. SOCRATES: And the account was supposed to be the expression of your distinguishing difference. THEAETETUS: Just so. SOCRATES: So then, when I was only judging, was I in my thinking touching on any of the things by which you differ from others? THEAETETUS: It seems not. SOCRATES: So I was thinking of one of the common features, none of which belongs to you any more than to anyone else. THEAETETUS: That must be so. SOCRATES: Then tell me, for God's sake — how, in that case, was I judging you rather than anyone else at all? Suppose I was thinking: this is Theaetetus, who is a human being and has a nose and eyes and a mouth, and so on for each of his limbs. Will that thought make me think of Theaetetus any more than of Theodorus, or of the most remote of the so-called Mysians? THEAETETUS: How could it? SOCRATES: But suppose I think not just of someone with a nose and eyes, but of someone snub-nosed and bug-eyed — will I then be judging you any more than myself, or anyone else like that? THEAETETUS: Not at all. SOCRATES: No — I don't think Theaetetus will be judged to be in my mind until this particular snubness has left in me some record distinguishing it from all the other snubnesses I've seen, and settled there — and likewise with everything else that makes you up — so that if I meet you tomorrow, it will remind me and make me judge correctly about you. THEAETETUS: That's exactly true. SOCRATES: So correct judgment, too, would concern the distinguishing difference of each thing. THEAETETUS: So it appears. SOCRATES: Then what more could there be to adding an account to correct judgment? If it means further judging in what way something differs from other things, the instruction becomes quite absurd. THEAETETUS: How so? SOCRATES: Of things we already have a correct judgment about, in respect of how they differ from other things, it tells us to add a correct judgment as to how they differ from other things. On this reading, the twirling of a rod, or a pestle, or whatever else people talk about, wouldn't be a patch on this instruction — it would more fairly be called the guidance of a blind man. For to order us to take up, in addition, what we already have, so that we may learn what we already judge — that looks like the product of someone thoroughly benighted. THEAETETUS: Then tell me — what was it you were just about to say when you asked your question?

SOCRATES: If, my boy, "adding an account" means being told to come to know the distinguishing difference, rather than merely to judge it, then this would be a charming business, this business of the finest account of knowledge! For to come to know is, I take it, to acquire knowledge — right? THEAETETUS: Yes. SOCRATES: So then, it seems, if asked what knowledge is, our man will answer: correct judgment together with knowledge of the distinguishing difference. For on his view, that's what "adding an account" would amount to. THEAETETUS: So it seems. SOCRATES: And it's utterly simple-minded, when we're inquiring into what knowledge is, to say that it's correct judgment together with knowledge — whether of a distinguishing difference or of anything else at all. So neither perception, Theaetetus, nor true judgment, nor an account added on to true judgment, could be knowledge. THEAETETUS: It seems not. SOCRATES: So then, my friend, are we still pregnant and in labor over knowledge, or have we delivered everything? THEAETETUS: Yes, by Zeus — and thanks to you I've said more than I even had in me. SOCRATES: And doesn't our art of midwifery say that all of this was wind-eggs, not worth raising? THEAETETUS: Absolutely. SOCRATES: Well then, Theaetetus, if after this you ever try to become pregnant with other ideas, and if you do conceive, you'll be fuller of better things thanks to today's examination; and if you remain empty, you'll be less burdensome to the people around you, and gentler, since you'll soberly not think you know what you don't know. That much, and no more, is what my art can do — I know nothing that the others know, all those great and marvelous men who are and have been. This midwifery my mother and I received as our lot from a god — hers for women, mine for the young and noble and all who are beautiful. For now I must go to the King's Portico, to face the indictment Meletus has brought against me. But at dawn, Theodorus, let's meet here again.

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