157–158
Socrates
SOC. Let us, then, not neglect a point in which it is defective. The defect is found in connection with dreams and diseases, including insanity, and everything else that is said to cause illusions of sight and hearing and the other senses. For of course you know that in all these the doctrine we were just presenting seems admittedly to be refuted, because in them we certainly have false perceptions, and it is by no means true that everything is to each man which appears to him; on the contrary, nothing is which appears.
Theaetetus
THEAET. What you say is very true, Socrates.
Socrates
SOC. What argument is left, then, my boy, for the man who says that perception is knowledge and that in each case the things which appear are to the one to whom they appear?
Theaetetus
THEAET. I hesitate to say, Socrates, that I have no reply to make, because you scolded me just now when I said that. But really I cannot dispute that those who are insane or dreaming have false opinions, when some of them think they are gods and others fancy in their sleep that they have wings and are flying.
Socrates
SOC. Don’t you remember, either, the similar dispute about these errors, especially about sleeping and waking?
Theaetetus
THEAET. What dispute?
5
Socrates
SOC. One which I fancy you have often heard. The question is asked, what proof you could give if anyone should ask us now, at the present moment, whether we are asleep and our thoughts are a dream, or whether we are awake and talking with each other in a waking condition.
