ve not all things words expressive of them?

Yes.

Of their existence or of their non-existence?

Of their existence.

Yes, Ctesippus, and we just now proved, as you may remember, that no man
could affirm a negative; for no one could affirm that which is not.

And what does that signify? said Ctesippus; you and I may contradict all
the same for that.

But can we contradict one another, said Dionysodorus, when both of us
are describing the same thing? Then we must surely be speaking the same
thing?

He assented.

Or when neither of us is speaking of the same thing? For then neither of
us says a word about the thing at all?

He granted that proposition also.

But when I describe something and you describe another thing, or I say
something and you say nothing--is there any contradiction? How can he
who speaks contradict him who speaks not?

Here Ctesippus was silent; and I in my astonishment said: What do you
mean, Dionysodorus? I have often heard, and have been amazed to hear,
this thesis of yours, which is maintained and employed by the disciples
of Protagoras, and others before them, and which to me appears to be
quite wonderful, and suicidal as well as destructive, and I think that
I am most likely to hear the truth about it from you. The dictum is that
there is no such thing as falsehood; a man must either say what is true
or say nothing. Is not that your position?

He assented.

But if he cannot speak falsely, may he not think falsely?

No, he cannot, he said.

Then there is no such thing as false opinion?

No, he said.

Then there is no such thing as ignorance, or men who are ignorant; for
is not ignorance, if there be such a thing, a mistake of fact?

Certainly, he said.

And that is impossible?

Impossible, he replied.

Are you saying this as a paradox, Dionysodorus; or do you seriously
maintain no man to be ignorant?

Refute me, he said.

But how can I refute you, if, as you say, to tell a falsehood is
impossible?

Very true, said Euthydemus.

Neither did I tell you just now to refute me, said Dionysodorus; for how
can I tell you to do that which is not?

O Euthydemus, I said, I have but a dull conception of these subtleties
and excellent devices of wisdom; I am afraid that I hardly understand
them, and you must forgive me therefore if I ask a very stupid question:
if there be no falsehood or false opinion or ignorance, there can be no
such thing as erroneous action, for a man