Stranger: And now tell me another thing.
Theaetetus: What?
Stranger: Is the not-beautiful anything but this—an existence parted off from a certain kind of existence, and again from another point of view opposed to an existing something?
Theaetetus: True.
Stranger: Then the not-beautiful turns out to be the opposition of being to being?
Theaetetus: Very true.
Stranger: But upon this view, is the beautiful a more real and the not-beautiful a less real existence?
Theaetetus: Not at all.
Stranger: And the not-great may be said to exist, equally with the great?
Theaetetus: Yes.
Stranger: And, in the same way, the just must be placed in the same category with the not-just—the one cannot be said to have any more existence than the other.
Theaetetus: True.
Stranger: The same may be said of other things; seeing that the nature of the other has a real existence, the parts of this nature must equally be supposed to exist.
Theaetetus: Of course.
Stranger: Then, as would appear, the opposition of a part of the other, and of a part of being, to one another, is, if I may venture to say so, as truly essence as being itself, and implies not the opposite of being, but only what is other than being.
Theaetetus: Beyond question.
Stranger: What then shall we call it?
Theaetetus: Clearly, not-being; and this is the very nature for which the Sophist compelled us to search.
Stranger: And has not this, as you were saying, as real an existence as any other class? May I not say with confidence that not-being has an assured existence, and a nature of its own? Just as the great was found to be great and the beautiful beautiful, and the not-great not-great, and the not-beautiful not-beautiful, in the same manner not-being has been found to be and is not-being, and is to be reckoned one among the many classes of being. Do you, Theaetetus, still feel any doubt of this?
Theaetetus: None whatever.
Stranger: Do you observe that our scepticism has carried us beyond the range of Parmenides’ prohibition?
Theaetetus: In what?
Stranger: We have advanced to a further point, and shown him more than he forbad us to investigate.
Theaetetus: How is that?
Stranger: Why, because he says—