Theaetetus (163)

THEAET. That would not be right, Socrates; neither you nor we would think so.

SOC. Apparently, then, you and Theodorus mean we must look at the matter in a different way.

THEAET. Yes, certainly in a different way.

SOC. Well, then, let us look at it in this way, raising the question whether knowledge is after all the same as perception, or different. For that is the object of all our discussion, and it was to answer that question than we stirred up all these strange doctrines, was it not?

THEAET. Most assuredly.

SOC. Shall we then agree that all that we perceive by sight or hearing we know? For instance, shall we say that before having learned the language of foreigners we do not hear them when they speak, or that we both hear and know what they say? And again, if we do not know the letters, shall we maintain that we do not see them when we look at them or that if we really see them we know them?

THEAET. We shall say, Socrates, that we know just so much of them as we hear or see: in the case of the letters, we both see and know the form and color, and in the spoken language we both hear and at the same time know the higher and lower notes of the voice; but we do not perceive through sight or hearing, and we do not know, what the grammarians and interpreters teach about them.

SOC. First-rate, Theaetetus! and it is a pity to dispute that, for I want you to grow. But look out for another trouble that is yonder coming towards us, and see how we can repel it.

THEAET. What is it?

SOC. It is like this: If anyone should ask, Is it possible, if a man has ever known a thing and still has and preserves a memory of that thing, that he does not, at the time when he remembers, know that very thing which he remembers? I seem to be pretty long winded; but I merely want to ask if a man who has learned a thing does not know it when he remembers it.

THEAET. Of course he does, Socrates; for what you suggest would be monstrous.

SOC. Am I crazy, then? Look here. Do you not say that seeing is perceiving and that sight is perception?

THEAET. I do.

SOC. Then, according to what we have just said, the man who has seen a thing has acquired knowledge of that which he has seen?

THEAET. Yes.

SOC. Well, then, do you not admit that there is such a thing as memory?

THEAET. Yes.

SOC. Memory of nothing or of something?

THEAET. Of something, surely.

SOC. Of things he has learned and perceived—that sort of things?

THEAET. Of course.

SOC. A man sometimes remembers what he has seen, does he not?

THEAET. He does.

SOC. Even when he shuts his eyes, or does he forget if he does that?

THEAET. It would be absurd to say that, Socrates.