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?