SOCRATES: And is it not shameless when we do not know what knowledge is, to be explaining the verb 'to know'? The truth is, Theaetetus, that we have long been infected with logical impurity. Thousands of times have we repeated the words 'we know,' and 'do not know,' and 'we have or have not science or knowledge,' as if we could understand what we are saying to one another, so long as we remain ignorant about knowledge; and at this moment we are using the words 'we understand,' 'we are ignorant,' as though we could still employ them when deprived of knowledge or science.
THEAETETUS: But if you avoid these expressions, Socrates, how will you ever argue at all?
SOCRATES: I could not, being the man I am. The case would be different if I were a true hero of dialectic: and O that such an one were present! for he would have told us to avoid the use of these terms; at the same time he would not have spared in you and me the faults which I have noted. But, seeing that we are no great wits, shall I venture to say what knowing is? for I think that the attempt may be worth making.
THEAETETUS: Then by all means venture, and no one shall find fault with you for using the forbidden terms.
SOCRATES: You have heard the common explanation of the verb 'to know'?
THEAETETUS: I think so, but I do not remember it at the moment.
SOCRATES: They explain the word 'to know' as meaning 'to have knowledge.'
THEAETETUS: True.
SOCRATES: I should like to make a slight change, and say 'to possess' knowledge.
THEAETETUS: How do the two expressions differ?