The Divine Institutes

After him Socrates held the first place in philosophy, who was pronounced most wise even by the oracle, because he confessed that he knew one thing only,—namely, that he knew nothing. And on the authority of this oracle it was right that the natural philosophers should restrain themselves, lest they should either inquire into those things which they could not know, or should think that they knew things which they did not know. Let us, however, see whether Socrates was most wise, as the Pythian god proclaimed. He often made use of this proverb, that that which is above us has also no reference to us. He has now passed beyond the limits of his opinion. For he who said that he knew one thing only, found another thing to speak of, as though he knew it; but that in vain. For God, who is plainly above us, is to be sought for; and religion is to be undertaken, which alone separates us from the brutes, which indeed Socrates not only rejected, but even derided, in swearing by a goose and a dog, as if in truth he could not have sworn by Æsculapius, to whom he had vowed a cock. Behold the sacrifice of a wise man! And because he was unable to offer this in his own person, since he was at the point of death, he entreated his friends to perform the vow after his death, lest forsooth he should be detained as a debtor in the lower regions. He assuredly both pronounced that he knew nothing, and made good his statement.