Stranger: And is therefore not the same.
Theaetetus: It is not.
Stranger: Yet, surely, motion is the same, because all things partake of the same.
Theaetetus: Very true.
Stranger: Then we must admit, and not object to say, that motion is the same and is not the same, for we do not apply the terms “same” and “not the same,” in the same sense; but we call it the “same,” in relation to itself, because partaking of the same; and not the same, because having communion with the other, it is thereby severed from the same, and has become not that but other, and is therefore rightly spoken of as “not the same.”
Theaetetus: To be sure.
Stranger: And if absolute motion in any point of view partook of rest, there would be no absurdity in calling motion stationary.
Theaetetus: Quite right—that is, on the supposition that some classes mingle with one another, and others not.
Stranger: That such a communion of kinds is according to nature, we had already proved before we arrived at this part of our discussion.
Theaetetus: Certainly.
Stranger: Let us proceed, then. May we not say that motion is other than the other, having been also proved by us to be other than the same and other than rest?
Theaetetus: That is certain.
Stranger: Then, according to this view, motion is other and also not other?
Theaetetus: True.
Stranger: What is the next step? Shall we say that motion is other than the three and not other than the fourth—for we agreed that there are five classes about and in the sphere of which we proposed to make enquiry?
Theaetetus: Surely we cannot admit that the number is less than it appeared to be just now.
Stranger: Then we may without fear contend that motion is other than being?
Theaetetus: Without the least fear.
Stranger: The plain result is that motion, since it partakes of being, really is and also is not?
Theaetetus: Nothing can be plainer.
Stranger: Then not-being necessarily exists in the case of motion and of every class; for the nature of the other entering into them all, makes each of them other than being, and so nonexistent; and therefore of all of them, in like manner, we may truly say that they are not; and again, inasmuch as they partake of being, that they are and are existent.
Theaetetus: So we may assume.
Stranger: Every class, then, has plurality of being and infinity of not-being.
Theaetetus: So we must infer.
Stranger: And being itself may be said to be other than the other kinds.