SOCRATES: And yet, my friend, I rather suspect that the result would have been different if Protagoras, who was the father of the first of the two brats, had been alive; he would have had a great deal to say on their behalf. But he is dead, and we insult over his orphan child; and even the guardians whom he left, and of whom our friend Theodorus is one, are unwilling to give any help, and therefore I suppose that I must take up his cause myself, and see justice done? THEODORUS: Not I, Socrates, but rather Callias, the son of Hipponicus, is guardian of his orphans. I was too soon diverted from the abstractions of dialectic to geometry. Nevertheless, I shall be grateful to you if you assist him. SOCRATES: Very good, Theodorus; you shall see how I will come to the rescue. If a person does not attend to the meaning of terms as they are commonly used in argument, he may be involved even in greater paradoxes than these. Shall I explain this matter to you or to Theaetetus? THEODORUS: To both of us, and let the younger answer; he will incur less disgrace if he is discomfited. SOCRATES: Then now let me ask the awful question, which is this:--Can a man know and also not know that which he knows? THEODORUS: How shall we answer, Theaetetus? THEAETETUS: He cannot, I should say. SOCRATES: He can, if you maintain that seeing is knowing. When you are imprisoned in a well, as the saying is, and the self-assured adversary closes one of your eyes with his hand, and asks whether you can see his cloak with the eye which he has closed, how will you answer the inevitable man? THEAETETUS: I should answer, 'Not with that eye but with the other.' SOCRATES: Then you see and do not see the same thing at the same time. THEAETETUS: Yes, in a certain sense. SOCRATES: None of that, he will reply; I do not ask or bid you answer in what sense you know, but only whether you know that which you do not know. You have been proved to see that which you do not see; and you have already admitted that seeing is knowing, and that not-seeing is not-knowing: I leave you to draw the inference. THEAETETUS: Yes; the inference is the contradictory of my assertion.