Commentary Aristotle Physics
About this, he does two things: first, he raises questions and solves them; second, he explains certain matters that may still be doubtful in regard to these questions, at “with regard to coming” (231a5; [747]).
The first part is divided into three sections, one for each question he raises.
About the first point he does two things: first, he raises a question; second, he solves it, at “we answer that, if” (230a29; [740]).
738. Therefore he first (230a18) raises the question why it is that, in the genus of local motion, but not in the other genera, there are found some motions and rests that are according to nature and some outside of nature. For example, why is it that there are alterations according to nature but none outside of nature? For getting well does not seem to be according to nature or outside of nature any more than getting sick, since each originates from a natural intrinsic principle. The same is true in regard to turning white and turning black or in growing and decreasing, for the former motions are not so contrary to one another that one is according to nature and the other outside of it, since each is a natural process. Nor is one growing contrary to another growing in such a way that one is according to nature and the other outside of it. The same is true of generation and ceasing to be, for generation cannot be said to be according to nature and ceasing to be outside of it, for growing old—which is the road to ceasing to be—is according to nature. Nor does it appear that one generation is according to nature and another outside of it.
739. Now, it seems that what he says here is opposed to a declaration in De caelo 2.6 that old age and every defect and ceasing to be are against nature. But it must be said that old age and ceasing to be and decreasing are against nature in one sense and according to nature in another. For if we consider the specific nature of anything—that is, its particular nature—it is clear that all ceasing to be and all defects and decrease are against nature, because each thing’s nature tends to preserve the subject in which it exists, whereas the contrary of this happens when the nature is weak or defective.
But, if we consider nature in general, all these things are the result of a natural intrinsic principle, as the destruction of an animal results from the contrariety of hot and cold; and the same is true for all the others.
740. Then, at “we answer that, if” (230a29), he answers this question by invalidating it.
About this, he does two things: first, he shows that things according to nature and outside of nature are found in every genus; second, he shows how these two things are contrary when they occur in motions and in states of rest, at “now, motions and states” (230b10; [742]).
About the first, he does two things: first, he determines the truth; second, he removes an objection, at “but it may be objected” (230b6; [741]).
He says first (230a29) that, since what takes place through force is outside of nature (because force arises from a principle outside a thing in such a way that the thing suffering force does not cooperate, whereas what is natural comes from an intrinsic principle), it follows that forced ceasing to be is contrary to natural ceasing to be, just as a ceasing to be that is outside of nature is opposed to one according to nature.
According to the same argument, he concludes that some generations are by force and not according to fate—that is, not according to the order of natural causes (because the order of natural causes can be called “fate”)—as when a person grows roses or fruits by artificial means out of season or when the generation of frogs or other natural things is procured artificially. Consequently, since these generations are by force, they are outside of nature and are contrary to generations according to nature.
He shows the same for growing and decreasing. For some cases of growth are by force and outside of nature, as is evident in persons who reach the state of puberty in an abnormally short time on account of soft living or on account of their food; that is, they are fed abundantly and delicately. The same is also apparent in the growing of wheat, for sometimes the grains grow unnaturally through abundance of moisture and are not compact (that is, made thick and solid by normal digestion).
It is likewise in alterations. Some are by force and some natural, as is especially evident in the process of getting well. For some recover from fever on the critical days and some not on the critical days. The former are cured according to nature and the latter outside of nature.
741. Then, at “but it may be objected” (230b6), he raises an objection against the foregoing. For since what is outside nature is contrary to what is according to nature, if there are some generations that are according to nature and some not (and the same for ceasing to be), it follows that instances of ceasing to be are contrary not to generation, but to one another, because one thing cannot be contrary to two.
But he solves this by saying that there is nothing to prevent generation from being contrary to generation and ceasing to be to ceasing to be. This is true even if you were to abstract from the contrariety between what is according to nature and what is outside of nature.
For if you take the case of something sweet coming to be and then ceasing to be, and the case of something sad coming to be and ceasing to be, the two cases of coming to be would be contrary and the two of ceasing to be would be contrary.
When he speaks of the coming to be and the ceasing to be of the sweet, he means when something more noble comes to be from the less noble that has ceased to be, as when fire is generated from air;
on the other hand, the coming to be and ceasing to be of the sad refers to the less noble coming to be from the ceasing to be of the more noble, as when air is generated from fire.
Now, even though ceasing to be is contrary to ceasing to be, it does not follow that it is not opposed to coming to be, for ceasing to be is opposed to coming to be when both are taken generically, while ceasing to be is opposed to ceasing to be in a specific sense. For example, avarice is contrary to liberality in the way that a vice is contrary to a virtue, but it is opposed to prodigality as one species to another. Thus, what he concludes is that ceasing to be is contrary to ceasing to be not simply—that is, in a generic sense—but one ceasing to be is this and another that—that is, by force and outside of nature, or sweet and sad.
742. Then, at “now, motions and states” (230b10), he explains contrariety in motion and rest on the basis of their being outside nature and according to nature. And he says that not only is coming to be contrary to coming to be and to ceasing to be from the viewpoint of being outside nature and according to nature, but all motions and rests are in general contrary in this way. For example, an upward motion is contrary to a downward one (because up and down are contrarieties of place), and each of these motions is natural to certain bodies: fire is naturally carried upward, and earth downward.
And, again, in regard to each of these motions, one can take as contrary differences that which is according to nature and that which is outside of nature. And this is what he means when he says “contrary to one another,” namely, that the motions are differences; or he might mean that, in respect to the very bodies that are moved, there are contrary differences in their motions, namely, according to nature and outside their nature. For an upward motion is natural to fire, but a downward is outside of nature.
So, it is clear that a motion that is according to nature is contrary to one that is outside of nature. It is likewise for states of rest. For rest that is above is contrary to a downward motion. But rest above is not natural to earth, whereas a downward motion is. According to the foregoing, then, it is clear that rest that is outside of nature is contrary to the natural motion of the body involved, for even in the same body, motions are mutually contrary in the sense that the natural motion of one body is contrary to an unnatural motion of the same body. The same is true of rest, for some contrary rests will be according to nature, as rest above for fire and rest down for earth; others are outside of nature, as down for fire and up for earth.
743. Then, at “here, however, the question arises” (230b21), he raises the second question: has every state of rest that is not eternal a becoming, which becoming is called a coming to a standstill? This is done so that we will not understand coming to a standstill and “being at rest” to mean the same thing. Rather, coming to a standstill means “to arrive at a state of rest.” This perhaps sounds better in Greek.