SOCRATES: Here then we have one kind of motion. But when a thing, remaining on the same spot, grows old, or becomes black from being white, or hard from being soft, or undergoes any other change, may not this be properly called motion of another kind?
THEODORUS: I think so.
SOCRATES: Say rather that it must be so. Of motion then there are these two kinds, 'change,' and 'motion in place.'
THEODORUS: You are right.
SOCRATES: And now, having made this distinction, let us address ourselves to those who say that all is motion, and ask them whether all things according to them have the two kinds of motion, and are changed as well as move in place, or is one thing moved in both ways, and another in one only?
THEODORUS: Indeed, I do not know what to answer; but I think they would say that all things are moved in both ways.
SOCRATES: Yes, comrade; for, if not, they would have to say that the same things are in motion and at rest, and there would be no more truth in saying that all things are in motion, than that all things are at rest.
THEODORUS: To be sure.
SOCRATES: And if they are to be in motion, and nothing is to be devoid of motion, all things must always have every sort of motion?
THEODORUS: Most true.