sophist   

Theaet. True.
Str. I was doubtful before in which of them I should place the
Sophist, nor am I even now able to see clearly; verily he is a
wonderful and inscrutable creature. And now in the cleverest
manner he
has got into an impossible place.
Theaet. Yes, he has.
Str. Do you speak advisedly, or are you carried away at the moment
by the habit of assenting into giving a hasty answer?
Theaet. May I ask to what you are referring?
Str. My dear friend, we are engaged in a very difficult
speculation-there can be no doubt of that; for how a thing can
appear and seem, and not be, or how a man can say a thing
which is not
true, has always been and still remains a very perplexing question.
Can any one say or think that falsehood really exists, and
avoid being
caught in a contradiction? Indeed, Theaetetus, the task is a
difficult
one.
Theaet. Why?
Str. He who says that falsehood exists has the audacity to assert
the being of not-being; for this is implied in the possibility of
falsehood. But, my boy, in the days when I was a boy, the great
Parmenides protested against this doctrine, and to the end
of his life
he continued to inculcate the same lesson-always repeating both in
verse and out of verse:

Keep your mind from this way of enquiry, for never will you show
that not-being is

Such is his testimony, which is confirmed by the very expression
when sifted a little. Would you object to begin with the
consideration
of the words themselves?
Theaet. Never mind about me; I am only desirous that you should
carry on the argument in the best way, and that you should take me
with you.
Str. Very good; and now say, do we venture to utter the forbidden
word "not-being"?
Theaet. Certainly we do.
Str. Let us be serious then, and consider the question neither in
strife nor play: suppose that one of the hearers of Parmenides was
asked, "To is the term 'not-being' to be applied?"-do you know what
sort of object he would single out in reply, and what answer he
would make to the enquirer?
Theaet. That is a difficult question, and one not to be answered
at all by a person like myself.
Str. There is at any rate no difficulty in seeing that the
predicate
"not-being" is not applicable to any being.
Theaet. None, certainly.
Str. And if not to being, then not to something.
Theaet. Of course not.
Str. It is also plain, that in speaking of something we speak of
being, for to speak of an abstract something naked and isolated from
all being is impossible.
Theaet. Impossible.
Str. You mean by assenting to imply that he who says something
must say some one thing?
Theaet. Yes.
Str. Some in the singular (ti) you would say is the sign of one,
some in the dual (tine) of two, some in the plural (tines) of many?