SOCRATES: But has not that position been relinquished by us, because involving the absurdity that we should know and not know the things which we know? THEAETETUS: True. SOCRATES: Let us make the assertion in another form, which may or may not have a favourable issue; but as we are in a great strait, every argument should be turned over and tested. Tell me, then, whether I am right in saying that you may learn a thing which at one time you did not know? THEAETETUS: Certainly you may. SOCRATES: And another and another? THEAETETUS: Yes. SOCRATES: I would have you imagine, then, that there exists in the mind of man a block of wax, which is of different sizes in different men; harder, moister, and having more or less of purity in one than another, and in some of an intermediate quality. THEAETETUS: I see. SOCRATES: Let us say that this tablet is a gift of Memory, the mother of the Muses; and that when we wish to remember anything which we have seen, or heard, or thought in our own minds, we hold the wax to the perceptions and thoughts, and in that material receive the impression of them as from the seal of a ring; and that we remember and know what is imprinted as long as the image lasts; but when the image is effaced, or cannot be taken, then we forget and do not know. THEAETETUS: Very good. SOCRATES: Now, when a person has this knowledge, and is considering something which he sees or hears, may not false opinion arise in the following manner? THEAETETUS: In what manner? SOCRATES: When he thinks what he knows, sometimes to be what he knows, and sometimes to be what he does not know. We were wrong before in denying the possibility of this. THEAETETUS: And how would you amend the former statement?