Sayings of Socrates 13

I am called wise, for my hearers always imagine that I myself possess wisdom that I find wanting in others. But the truth is, O men of Athens, that god only is wise; and in this oracle he means to say that the wisdom of men is little or nothing. . . as if he said, he, O men, is the wisest, who like Socrates, knows that his wisdom is in truth worth nothing. 

And so I go on my way, obedient to the god, and make inquisition into anyone, whether citizen or stranger, who appears to be wise. And if he is not wise, then in vindication of the oracle I show him that he is not wise; and this occupation quite absorbs me, and I have no time to give either to any public matter of interest or to any concern of my own, but I am in utter poverty by reason of my devotion to the god.

—Plato, Apology, 23a-c