Soc. And you would admit that there is such a thing as memory?

  Theaet. Yes.

  Soc. And is memory of something or of nothing?

  Theaet. Of something, surely.

  Soc. Of things learned and perceived, that is?

  Theaet. Certainly.

  Soc. Often a man remembers that which he has seen?

  Theaet. True.

  Soc. And if he closed his eyes, would he forget?

  Theaet. Who, Socrates, would dare to say so?

  Soc. But we must say so, if the previous argument is to be
maintained.

  Theaet. What do you mean? I am not quite sure that I understand you,
though I have a strong suspicion that you are right.

  Soc. As thus: he who sees knows, as we say, that which he sees;
for perception and sight and knowledge are admitted to be the same.

  Theaet. Certainly.

  Soc. But he who saw, and has knowledge of that which he saw,
remembers, when he closes his eyes, that which he no longer sees.

  Theaet. True.

  Soc. And seeing is knowing, and therefore not-seeing is not-knowing?

  Theaet. Very true.

  Soc. Then the inference is, that a man may have attained the
knowledge, of something, which he may remember and yet not know,
because he does not see; and this has been affirmed by us to be a
monstrous supposition.

  Theaet. Most true.

  Soc. Thus, then, the assertion that knowledge and perception are
one, involves a manifest impossibility?