SOCRATES: You think, if I am not mistaken, that your 'truly false' is safe from censure, and that I shall never ask whether there can be a swift which is slow, or a heavy which is light, or any other self-contradictory thing, which works, not according to its own nature, but according to that of its opposite. But I will not insist upon this, for I do not wish needlessly to discourage you. And so you are satisfied that false opinion is heterodoxy, or the thought of something else?
THEAETETUS: I am.
SOCRATES: It is possible then upon your view for the mind to conceive of one thing as another?
THEAETETUS: True.
SOCRATES: But must not the mind, or thinking power, which misplaces them, have a conception either of both objects or of one of them?
THEAETETUS: Certainly.
SOCRATES: Either together or in succession?
THEAETETUS: Very good.
SOCRATES: And do you mean by conceiving, the same which I mean?
THEAETETUS: What is that?