Then the one which is not, if it is to maintain itself, must have the being of not-being as the bond of not-being, just as being must have as a bond the not-being of not-being in order to perfect its own being; for the truest assertion of the being of being and of the not-being of not-being is when being partakes of the being of being, and not of the being of not-being--that is, the perfection of being; and when not-being does not partake of the not-being of not-being but of the being of not-being--that is the perfection of not-being. Most true. Since then what is partakes of not-being, and what is not of being, must not the one also partake of being in order not to be? Certainly. Then the one, if it is not, clearly has being? Clearly. And has not-being also, if it is not? Of course. But can anything which is in a certain state not be in that state without changing? Impossible. Then everything which is and is not in a certain state, implies change? Certainly. And change is motion--we may say that? Yes, motion. And the one has been proved both to be and not to be? Yes. And therefore is and is not in the same state? Yes. Thus the one that is not has been shown to have motion also, because it changes from being to not-being? That appears to be true. But surely if it is nowhere among what is, as is the fact, since it is not, it cannot change from one place to another? Impossible. Then it cannot move by changing place? No. Nor can it turn on the same spot, for it nowhere touches the same, for the same is, and that which is not cannot be reckoned among things that are? It cannot. Then the one, if it is not, cannot turn in that in which it is not? No. Neither can the one, whether it is or is not, be altered into other than itself, for if it altered and became different from itself, then we could not be still speaking of the one, but of something else? True. But if the one neither suffers alteration, nor turns round in the same place, nor changes place, can it still be capable of motion? Impossible. Now that which is unmoved must surely be at rest, and that which is at rest must stand still? Certainly. Then the one that is not, stands still, and is also in motion? That seems to be true. But if it be in motion it must necessarily undergo alteration, for anything which is moved, in so far as it is moved, is no longer in the same state, but in another? Yes. Then the one, being moved, is altered? Yes. And, further, if not moved in any way, it will not be altered in any way? No. Then, in so far as the one that is not is moved, it is altered, but in so far as it is not moved, it is not altered? Right. Then the one that is not is altered and is not altered? That is clear. And must not that which is altered become other than it previously was, and lose its former state and be destroyed; but that which is not altered can neither come into being nor be destroyed? Very true.