Jowett: Theaetetus 151d-151e — Primeira definição: saber é a sensação

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.