SOCRATES: In the first place, how can a man who has the knowledge of anything be ignorant of that which he knows, not by reason of ignorance, but by reason of his own knowledge? And, again, is it not an extreme absurdity that he should suppose another thing to be this, and this to be another thing;--that, having knowledge present with him in his mind, he should still know nothing and be ignorant of all things?--you might as well argue that ignorance may make a man know, and blindness make him see, as that knowledge can make him ignorant. THEAETETUS: Perhaps, Socrates, we may have been wrong in making only forms of knowledge our birds: whereas there ought to have been forms of ignorance as well, flying about together in the mind, and then he who sought to take one of them might sometimes catch a form of knowledge, and sometimes a form of ignorance; and thus he would have a false opinion from ignorance, but a true one from knowledge, about the same thing. SOCRATES: I cannot help praising you, Theaetetus, and yet I must beg you to reconsider your words. Let us grant what you say--then, according to you, he who takes ignorance will have a false opinion--am I right? THEAETETUS: Yes. SOCRATES: He will certainly not think that he has a false opinion? THEAETETUS: Of course not. SOCRATES: He will think that his opinion is true, and he will fancy that he knows the things about which he has been deceived? THEAETETUS: Certainly. SOCRATES: Then he will think that he has captured knowledge and not ignorance? THEAETETUS: Clearly. SOCRATES: And thus, after going a long way round, we are once more face to face with our original difficulty. The hero of dialectic will retort upon us:--'O my excellent friends, he will say, laughing, if a man knows the form of ignorance and the form of knowledge, can he think that one of them which he knows is the other which he knows? or, if he knows neither of them, can he think that the one which he knows not is another which he knows not? or, if he knows one and not the other, can he think the one which he knows to be the one which he does not know? or the one which he does not know to be the one which he knows? or will you tell me that there are other forms of knowledge which distinguish the right and wrong birds, and which the owner keeps in some other aviaries or graven on waxen blocks according to your foolish images, and which he may be said to know while he possesses them, even though he have them not at hand in his mind? And thus, in a perpetual circle, you will be compelled to go round and round, and you will make no progress.' What are we to say in reply, Theaetetus? THEAETETUS: Indeed, Socrates, I do not know what we are to say. SOCRATES: Are not his reproaches just, and does not the argument truly show that we are wrong in seeking for false opinion until we know what knowledge is; that must be first ascertained; then, the nature of false opinion?