Theaetetus: How, Stranger, can I describe an image except as something fashioned in the likeness of the true?
Stranger: And do you mean this something to be some other true thing, or what do you mean?
Theaetetus: Certainly not another true thing, but only a resemblance.
Stranger: And you mean by true that which really is?
Theaetetus: Yes.
Stranger: And the not true is that which is the opposite of the true?
Theaetetus: Exactly.
Stranger: A resemblance, then, is not really real, if, as you say, not true?
Theaetetus: Nay, but it is in a certain sense.
Stranger: You mean to say, not in a true sense?
Theaetetus: Yes; it is in reality only an image.
Stranger: Then what we call an image is in reality really unreal.
Theaetetus: In what a strange complication of being and not-being we are involved!
Stranger: Strange! I should think so. See how, by his reciprocation of opposites, the many-headed Sophist has compelled us, quite against our will, to admit the existence of not-being.
Theaetetus: Yes, indeed, I see.
Stranger: The difficulty is how to define his art without falling into a contradiction.
Theaetetus: How do you mean? And where does the danger lie?
Stranger: When we say that he deceives us with an illusion, and that his art is illusory, do we mean that our soul is led by his art to think falsely, or what do we mean?
Theaetetus: There is nothing else to be said.
Stranger: Again, false opinion is that form of opinion which thinks the opposite of the truth:—You would assent?
Theaetetus: Certainly.
Stranger: You mean to say that false opinion thinks what is not?
Theaetetus: Of course.
Stranger: Does false opinion think that things which are not are not, or that in a certain sense they are?
Theaetetus: Things that are not must be imagined to exist in a certain sense, if any degree of falsehood is to be possible.