Commentary Aristotle Physics
974. But, if one considers rightly, he was deceived by a cause similar to the cause by which he claimed we are deceived: by considering particular things. For it is clear that a particular active power presupposes the matter that a more universal agent produces, just as an artisan uses the matter that nature makes. Therefore, from the fact that every particular agent presupposes matter that it does not produce, one should not suppose that the first universal agent—which is active with respect to all being—should presuppose something not caused by it.
Nor is this in keeping with the intention of Aristotle, who, in Metaphysics 2, proves that the supremely true and the supreme being is the cause of being for all existents. Hence the being that prime matter has—namely, being in potency—is derived from the first principle of being, which is a being in a supreme way. Therefore, it is not necessary to presuppose for its action anything not produced by it.
And because every motion needs a subject (as Aristotle proves here, and as is the truth of the matter), it follows that the universal production of being by God is neither motion nor change, but a certain simple coming forth. Consequently, “to be made” and “to make” are used in an equivocal sense when applied to this universal production of being and to other productions.
Therefore, just as, if we should understand the production of things to be from God from eternity, as Aristotle and a number of the Platonists supposed, it is not necessary—indeed, it is impossible—that there have been a preexisting but unproduced subject of this universal production, so also, in accord with the tenets of our faith, if we posit that he did not produce things from eternity, but produced them after they had not existed, it is not necessary to posit a subject for this universal production.
It is evident, therefore, that what Aristotle proves here (namely, that every motion requires a mobile subject) is not against a tenet of our faith, for it has already been said that the universal production of things, whether from eternity or not, is neither a motion nor a change. For in order that there be motion or change, it is required that something be otherwise now than previously, and thus there would be something previously existing, and consequently, this would not be the universal production of things about which we are now speaking.
975. Similarly, Averroes’ statement that something is said to come to be from its opposite per accidens and from a subject per se is true in particular productions according to which this or that being comes to be (such as a man or a dog), but is not true in the universal production of being.
This is clear from what the Philosopher said in Physics 1. For he said there that, if this animal comes to be inasmuch as it is this animal, it ought not to come to be from “non-animal,” but from “non-this-animal”—for example, if a man comes to be from non-man or a horse from non-horse.
But, if animal is produced precisely as animal, it must come to be from non-animal. Accordingly, if some particular being comes to be, it does not come to be from absolute non-being; but if the whole being comes to be (that is, if being precisely as being comes to be), it must be made from absolute non-being—if this should still be called “being made,” for it is an equivocal way of speaking, as has been said.
What Averroes introduces about the early philosophers has no value, for they were unable to arrive at the first cause of all being, but considered the causes of particular changes.
The first of these philosophers considered the causes solely of accidental changes, and posited all “being made” to be alteration. Those who succeeded them arrived at a knowledge of substantial changes, but those who came still later, such as Plato and Aristotle, arrived at a knowledge of the principle of all existence.
Consequently, it is clear that we are not moved to assert that something comes to be from nothing because we suppose only visible things to be beings; rather, it is because we do not content ourselves with considering merely the particular productions of particular causes, but go on to consider the universal production of all being from the first principle of being.
Nor do we assert that to need matter in order to act is due to a diminished power, in the sense of such a power lacking its natural energy; rather, what we say is that this is proper to a particular power, which does not extend to all being but makes a particular being.
Hence, one can say that it is characteristic of a diminished power to make something from something in the sense that we would say that a particular power is less than the universal power.
976. Then, at “moreover, these things also” (251a16), assuming that a mobile and a mover are required in order that there be motion, Aristotle argues in the following manner. If motion has not always existed, it is necessary to say either that mobiles and movers were at some time made, having previously not existed, or are eternal.
If, therefore, it is held that each mobile has been made, it is necessary to say that, prior to the change that is taken as the first, there was another change and motion according to which was made the very mobile that is able to be moved and to have been moved.
This inference, indeed, depends on the preceding. For if it is granted that motion has not always been, but that there is some first change before which there was none, it will follow that that first change involved a mobile and that that mobile was made, for previously, it did not exist—since it is being supposed that all mobiles have been made.
Now, whatever comes to be after having previously not existed comes to be through a motion or a change. But the motion or change through which a mobile comes to be is prior to the change by which the mobile is moved. Therefore, prior to the change that was presumed to be first, there is another change, and so on to infinity.
But, if it is held that things that are mobile always preexisted, even when no motion existed, this seems to be unreasonable and a sign of ignorance. For it immediately appears that, if mobiles exist, motion ought to exist, for natural mobiles are at once also movers, as is clear from book 3. But, if natural mobiles and movers are existing, there must be motion.
But, to enter more deeply into our search for the truth, it is necessary that this same thing happen—if mobiles and movers are assumed to be eternally existing prior to motion—that followed from the assumption that they were made: prior to the change supposed to be the first, there is another change, and so on to infinity.
This is evident in the following way. If it be supposed that certain mobiles and certain movers exist, and yet the first mover begins at some time or other to cause motion and something is moved by it, and before this nothing is being moved, but is at rest, it will be necessary to say that there was another change in the mover or mobile made prior to that which was assumed to be the first one produced by the mover beginning to cause motion.
The truth of this is clear from the following. Rest is the privation of motion. Privation, however, is not present in a thing capable of habit and form except on account of some cause. Therefore, there was a cause—either on the part of the mover or on the part of the mobile—of why there was rest.
Hence, as long as that cause prevailed, there was always rest. If, then, a mover begins at some time to cause motion, the cause of rest must be removed. But it cannot be removed except by a motion or change. Therefore, it follows that, before that change that was said to be first, there is a prior change by which the cause of rest is removed.
977. Then, at “for some things cause motion” (251a28), he proves the necessity of the foregoing argument. For someone could say that it happens that things are at rest at some time and in motion at some time without any preexisting cause of rest to be removed. Hence, he wishes to refute this.
And about this, he does two things: first, he sets down something needed for his proof; second, he presents the proposed proof, at “but, at any rate” (251b1; [978]).
He says first that, among movers, some move singularly, in just one way, while others move with respect to motions that are contrary. Things that cause motion in just one way are natural things, as fire always heats and never cools. But beings that act through intellect are causes of motions that are contrary, for one and the same knowledge seems to deal with things and their contraries, as medicine is the science of health and of sickness. Hence, one sees that a doctor, by means of his science, can cause motions that are mutually contrary.
Now, Aristotle mentioned this distinction among movers because, in things that act through intellect, it does not appear that what he had said is true—that, if something is moved when previously it had been at rest, the cause of the rest ought first be removed. For things that act according to intellect seem to be ready to move to opposites without any change of themselves being involved; hence it seems that, without any change, they can cause motion and not cause it.
Therefore, lest his argument be forestalled by this objection, he adds that his reason holds both for things that act according to intellect and for those that act by nature. For things that act by nature do always per se move to one, but per accidens they sometimes move to the contrary, and in order that such an accident occur, some change is necessary; thus, cold always per se causes coldness, but per accidens it produces warmth.
But that cold should per accidens cause warmth is due to some change affecting the cold object, either inasmuch as it is moved to another location (so that it now relates in a different way to the thing that now is heated by it than it related while chilling it), or inasmuch as it completely departs.
For we say that cold is the cause of warmth by departing in the way that a captain is, by his absence, the cause of the sinking of a ship. Again, cold becomes per accidens the cause of warmth either by moving farther away or by approaching closer, as in the winter, the interior of animals is warmer, because their heat retreats inward on account of the surrounding cold.
The same applies to things that act by intellect. For although knowledge is one thing dealing with contraries, it does not deal equally with them both, but with one principally, as medicine is per se ordained to causing health. Therefore, if it happens that a doctor uses his knowledge for the contrary purpose of causing sickness, this will not be per se from this science, but per accidens, on account of something else. And, in order that something else occur when previously it did not exist, some change is required.