were ready to bite me when I deprived them of a darling folly; they
did not perceive that I acted from good will, not knowing that no
god is the enemy of man-that was not within the range of their
ideas; neither am I their enemy in all this, but it would be wrong for
me to admit falsehood, or to stifle the truth. Once more, then,
Theaetetus, I repeat my old question, "What is knowledge?"-and do
not say that you cannot tell; but quit yourself like a man, and by the
help of God you will be able to tell.

  Theaet. At any rate, Socrates, after such an exhortation I should be
ashamed of not trying to do my best. Now he who knows perceives what
he knows, and, as far as I can see at present, knowledge is
perception.

  Soc. Bravely said, boy; that is the way in which you should
express your opinion. And now, let us examine together this conception
of yours, and see whether it is a true birth or a mere,
wind-egg:-You say that knowledge is perception?

  Theaet. Yes.

  Soc. Well, you have delivered yourself of a very important
doctrine about knowledge; it is indeed the opinion of Protagoras,
who has another way of expressing it, Man, he says, is the measure
of all things, of the existence of things that are, and of the
non-existence of things that are not:-You have read him?

  Theaet. O yes, again and again.

  Soc. Does he not say that things are to you such as they appear to
you, and to me such as they appear to me, and that you and I are men?

  Theaet. Yes, he says so.

  Soc. A wise man is not likely to talk nonsense. Let us try to
understand him: the same wind is blowing, and yet one of us may be
cold and the other not, or one may be slightly and the other very
cold?

  Theaet. Quite true.

  Soc. Now is the wind, regarded not in relation to us but absolutely,
cold or not; or are we to say, with Protagoras, that the wind is
cold to him who is cold, and not to him who is not?

  Theaet. I suppose the last.

  Soc. Then it must appear so to each of them?

  Theaet. Yes.