ing, but of some
other;--when the various numbers and forms of knowledge are flying about
in the aviary, and wishing to capture a certain sort of knowledge out
of the general store, he takes the wrong one by mistake, that is to say,
when he thought eleven to be twelve, he got hold of the ring-dove which
he had in his mind, when he wanted the pigeon.

THEAETETUS: A very rational explanation.

SOCRATES: But when he catches the one which he wants, then he is not
deceived, and has an opinion of what is, and thus false and true opinion
may exist, and the difficulties which were previously raised disappear.
I dare say that you agree with me, do you not?

THEAETETUS: Yes.

SOCRATES: And so we are rid of the difficulty of a man's not knowing
what he knows, for we are not driven to the inference that he does not
possess what he possesses, whether he be or be not deceived. And yet I
fear that a greater difficulty is looking in at the window.

THEAETETUS: What is it?

SOCRATES: How can the exchange of one knowledge for another ever become
false opinion?

THEAETETUS: What do you mean?

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