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 cannot fail of acting as he is acting--that is
what you mean?

Yes, he replied.

And now, I said, I will ask my stupid question: If there is no such thing
as error in deed, word, or thought, then what, in the name of goodness, do
you come hither to teach? And were you not just now saying that you could
teach virtue best of all men, to any one who was willing to learn?

And are you such an old fool, Socrates, rejoined Dionysodorus, that you
bring up now what I said at first--and if I had said anything last year, I
suppose that you would bring that up too--but are non-plussed at the words
which I have just uttered?

Why, I said, they are not easy to answer; for they are the words of wise
men: and indeed I know not what to make of this word 'nonplussed,' which
you used last: what do you mean by it, Dionysodorus? You must mean that I
cannot refute your argument. Tell me if the words have any other sense.

No, he replied, they mean what you say. And now answer.