Commentary Aristotle Physics
Lecture 9
The contrariety of rest to motion and rest to rest
But since a motion appears to have contrary to it not only another motion but also a state of rest, we must determine how this is so.
A motion has for its contrary in the strict sense of the term another motion, but it also has for an opposite a state of rest (for rest is the privation of motion and the privation of anything may be called its contrary).
And motion of one kind has for its opposite rest of that kind (for instance, local motion has local rest).
This statement, however, is said simply, and needs further qualification: there remains the question whether the opposite of rest at a particular place is motion from or motion to that place.
It is surely clear that, since there are two subjects between which motion takes place, motion from one of these (A) to its contrary (B) has for its opposite remaining in A, while the reverse motion has for its opposite remaining in B.
At the same time these two are also contrary to each other, since it would be absurd to suppose that there are contrary motions and not opposite states of rest. States of rest in contraries are opposed. To take an example, a state of rest in health is contrary to a state of rest in disease.
But the motion to which it is contrary is that from health to disease. It would be absurd that its contrary motion should be that from disease to health, since motion to that in which a thing is at rest is rather a coming to rest in itself, since it happens to come to be simultaneously with the motion; and it must be one of these two motions. And rest in whiteness is, of course, not contrary to rest in health.
Of all things that have no contraries, there are opposite changes (namely, change from the thing and change to the thing, such as change from being and change to being), but no motion.
So, too, of such things, there is no remaining, though there is absence of change.
Should there be a particular subject, absence of change in its being will be contrary to absence of change in its non-being.
And here a difficulty may be raised: if there is nothing that is not, it may be asked what it is that is contrary to absence of change in a thing’s being. And is this absence of change a state of rest?
If it is, then either it is not true that every state of rest is contrary to a motion or else generation and ceasing to be are motion. It is clear, then, that, since we exclude these from among motions, we must not say that this absence of change is a state of rest.
We must say that it is similar to a state of rest and call it absence of change.
And it will have for its contrary either nothing or absence of change in the thing’s non-being, or the ceasing to be of the thing, for such ceasing to be is change from it and the thing’s generation is change to it.
727. After discussing contrariety of motions, the Philosopher now determines about contrariety of rest: first, in the case of motions; second, in the case of changes, at “of all things that have” (230a7; [732]).
About the first, he does two things: first, he shows how rest is contrary to motion; second, which is contrary to which, at “and motion of one kind” (229b26; [728]).
He says first (229b23) that, since not only motion but also rest seem to be contrary to motion, we have to decide how rest is contrary to motion, for strictly speaking, it is motion that is perfectly contrary to motion. However, even rest is opposed to motion, since it is the privation of motion, and privation is somehow a contrary. For privation and possession form the fundamental contraries, as is said in Metaphysics 10, since the ideas of privation and possession are involved in every type of contrary, inasmuch as, in any set of contraries, one of them is as privation in respect of the other—for example, black in relation to white and sweet in relation to bitter.
728. Then, at “and motion of one kind” (229b26), he shows which rest is contrary to which motion.
About this, he does three things: first, he phrases the question; second, he determines the truth, at “it is surely clear” (229b29; [729]); third, he proves it, at “but the motion to which” (230a3; [731]).
In the question he proposes (229b26), he assumes that not just any state of rest is indiscriminately opposed to just any state of motion, but a definite type of rest to a definite type of motion; for example, rest in place is opposed to motion in regard to place. But because this is said simply, that is, generally, there still remains another problem: whether the opposite of that rest that consists in possessing its goal, such as whiteness, is the motion to whiteness—that is, whitening—or the one from whiteness, namely, blackening.
729. Then, at “it is surely clear” (229b29), he determines the truth.
First, as to the contrariety of motion to rest; second, as to the contrariety of rest to rest, at “at the same time” (229b31; [730]).
He says first (229b29) that, since motion is between two subjects, affirmed termini, the contrary of a motion from A to its contrary B is rest in A; for example, the contrary of a motion from whiteness to blackness is rest in whiteness, while the contrary of a motion from the contrary B to A is rest in B—for example, the contrary of a motion from black to white is rest in black.
730. Then, at “at the same time” (229b31), he treats of the contrariety of one state of rest to another. And he says that those states of rest that are in contrary termini are mutually contrary. For it is not suitable to have motions contrary to one another and states of rest not contrary. And how states of rest in opposites are opposite, he explains with the example that rest in health is the opposite of rest in sickness.
731. Then, at “but the motion to which” (230a3), he proves what he had said about the contrariety of rest to motion. And he says that the opposition of a motion from health to sickness is rest in health, for it is not reasonable that rest in health be the opposite of a motion from sickness to health. He now proves that rest in itself—that is, in the very goal toward which something else is in motion—is the consummation and perfection of that motion, rather than the opposite. And that rest in the goal toward which there is motion is its perfection is evident from the fact that the state of rest is coming to be during the motion, because the very motion toward the goal means that rest is coming to be. Hence, since motion is the cause of that rest, it cannot be its opposite, because a thing is not the cause of its opposite. Now, the contrary of a motion must be either rest in its goal or rest in the starting point. For it is not reasonable to say that rest in some other species is contrary to a given motion or rest, any more than rest in whiteness is contrary to rest in health or motion to health. Consequently, since rest in the goal is not contrary to motion toward that goal, the only thing that remains is that it is contrary to rest in the starting point.
732. Then, at “of all things that have” (230a7), he determines about contrariety of rest in changes.
About this, he does three things: first, he repeats what has already been said about contrariety of changes; second, he shows that the opposite of change is not rest, but non-change, at “so, too, of such things” (230a9; [733]); third, he shows how non-change is contrary to change, at “we must say that it is” (230a16; [736]).
He therefore first (230a7) repeats what was said above, namely, that, in changes that do not involve termini that are contrary—for example, in the generation and ceasing to be of substance—opposition is based on approach and departure from the same terminus: a change from a thing is opposed to a change to the thing as a change from being, or corruption, is opposed to a change to being, or generation. However, neither of these is called motion.
733. Then, at “so, too, of such things” (230a9), he shows that these changes do not have an opposing state of rest.
About this, he does three things: first, he proposes what he intends; second, he interposes a question, at “should there be a particular” (230a10; [734]); third, he proves his proposition, at “if it is, then either” (230a12; [735]).
He says first (230a9) that changes that do not pass from contrary to contrary have no states of rest opposed to them; rather, what is opposed to them in the way that rest is opposed to motion can be called “non-change.”
734. Then, at “should there be a particular” (230a10), he interposes a question on this matter. For it has been said that a change to being is contrary to a change from being, which is really a change to non-being.
Now, the expression “non-being” has two senses.