THEAETETUS: Why so?
STRANGER: The attempt at universal separation is the final annihilation of all reasoning; for only by the union of conceptions with one another do we attain to discourse of reason.
THEAETETUS: True.
STRANGER: And, observe that we were only just in time in making a resistance to such separatists, and compelling them to admit that one thing mingles with another.
THEAETETUS: Why so?
STRANGER: Why, that we might be able to assert discourse to be a kind of being; for if we could not, the worst of all consequences would follow; we should have no philosophy. Moreover, the necessity for determining the nature of discourse presses upon us at this moment; if utterly deprived of it, we could no more hold discourse; and deprived of it we should be if we admitted that there was no admixture of natures at all.
THEAETETUS: Very true. But I do not understand why at this moment we must determine the nature of discourse.
STRANGER: Perhaps you will see more clearly by the help of the following explanation.
THEAETETUS: What explanation?
STRANGER: Not-being has been acknowledged by us to be one among many classes diffused over all being.