sophist   

Str. Strange! I should think so. See how, by his reciprocation of
opposites, the many-headed Sophist has compelled us, quite
against our
will, to admit the existence of not-being.
Theaet. Yes, indeed, I see.
Str. The difficulty is how to define his art without falling into
a contradiction.
Theaet. How do you mean? And where does the danger lie?
Str. When we say that he deceives us with an illusion, and that
his art is illusory, do we mean that our soul is led by his art to
think falsely, or what do we mean?
Theaet. There is nothing else to be said.
Str. Again, false opinion is that form of opinion which thinks the
opposite of the truth:-You would assent?
Theaet. Certainly.
Str. You mean to say that false opinion thinks what is not?
Theaet. Of course.
Str. Does false opinion think that things which are not are not,
or that in a certain sense they are?
Theaet. Things that are not must be imagined to exist in a certain
sense, if any degree of falsehood is to be possible.
Str. And does not false opinion also think that things which most
certainly exist do not exist at all?
Theaet. Yes.
Str. And here, again, is falsehood?
Theaet. Falsehood-yes.
Str. And in like manner, a false proposition will be deemed to be
one which are, the nonexistence of things which are, and the
existence
of things which are not.
Theaet. There is no other way in which a false proposition can
arise.
Str. There is not; but the Sophist will deny these statements. And
indeed how can any rational man assent to them, when the very
expressions which we have just used were before acknowledged by us
to be unutterable, unspeakable, indescribable, unthinkable?
Do you see
his point, Theaetetus?
Theaet. Of course he will say that we are contradicting ourselves
when we hazard the assertion, that falsehood exists in opinion and
in words; for in maintaining this, we are compelled over and over
again to assert being of not-being, which we admitted just now to be
an utter impossibility.
Str. How well you remember! And now it is high time to hold a
consultation as to what we ought to do about the Sophist; for if we
persist in looking for him in the class of false workers and
magicians, you see that the handles for objection and the
difficulties
which will arise are very numerous and obvious.
Theaet. They are indeed.
Str. We have gone through but a very small portion of
them, and they
are really infinite.
Theaet. If that is the case, we cannot possibly catch the Sophist.
Str. Shall we then be so faint-hearted as to give him up?
Theaet. Certainly not, I should say, if we can get the slightest
hold upon him.
Str. Will you then forgive me, and, as your words imply, not be
altogether displeased if I flinch a little from the grasp of such a
sturdy argument?
Theaet. To be sure I will.
Str. I have a yet more urgent request to make.
Theaet. Which is-?
Str. That you will promise not to regard me as a parricide.