Tertullian · a new plain-English translation from the original language
If you demand a written law for this and other disciplines of the same kind, you will read none in Scripture. Tradition will be put forward as its author, custom as its confirmer, faith as its keeper. That reason stands behind tradition, custom, and faith you will either see for yourself or learn from someone who has seen it; meanwhile you will believe that some obedience is owed to it. I add one further example, since it is fitting to teach from ancient cases too. Among the Jews it is so much the settled practice for their women to veil the head that they are recognized by it. I ask for the law; I defer the apostle. If Rebecca, catching sight of her betrothed in the distance, snatched up a veil, private modesty could not make a law — or if it did make one for her own case, then let only virgins be veiled, and only when coming to be married, not before they have met their bridegrooms. If Susanna too, unveiled at her trial, furnishes an argument for veiling, I can say: here too the veil was a matter of choice. She had come as a defendant, blushing at her disgrace, rightly hiding her beauty, or else already afraid of pleasing. But I do not suppose that in the arena of marriage a woman who wished to please walked veiled. Suppose her veiled always — even there I still ask for a law of the practice, in her case or in any other. If nowhere do I find a law, it follows that tradition gave custom this habit, a habit destined one day to acquire apostolic authority through the interpretation of reason. By these examples, then, it will have been shown that even an unwritten tradition can be defended in its observance, confirmed by custom, with the persistence of the observance itself standing as competent witness that the tradition was once approved. Custom, moreover, is received as law even in civil affairs when statute is lacking, and it makes no difference whether it rests on writing or on reason, since reason too commends a law. Further, if a law stands on reason, then everything that stands on reason will already be law, from whatever quarter it is produced. Or do you not think it permitted to every believer to conceive and establish — provided only that it agree with God, serve discipline, and profit salvation — what the Lord means when he says: "And why do you not judge for yourselves what is right?" And it is not only of judgment but of every verdict in matters under examination that the apostle too speaks: "If you are ignorant of anything, God will reveal it to you" — he himself being accustomed to supply counsel when he had no command from the Lord, and to pronounce on his own authority, having the Spirit of God as guide into all truth. And so his counsel has already obtained the standing of a divine precept, under the patronage of divine reason. Demand this reason now, while preserving your regard for tradition, whoever the one who handed it down is credited to be — and attend not to whose hand delivered it but to the weight of authority behind it, and above all to that of custom itself, which is to be honored precisely because it may be reason's interpreter — so that, if God has given this too, you may then learn not whether custom is to be observed by you, but why.