Commentary Aristotle Physics
Lecture 3
In local motion, the mover and the moved must be together
The first mover, not as the cause for the sake of which, but as the principle of motion, is together with that which is moved. I say “together” because there is no intermediate between them. And this is found universally in everything that moves and is moved.
Since there are three motions, i.e., in respect to place, in respect to quality, and in respect to quantity, there must be three things that are moved. Motion in respect to place is local motion; motion in respect to quality is alteration; motion in respect to quantity is increase or decrease. We should speak first of local motion. For this is the first of motions.
Whatever is moved is moved either by itself or by another. If by itself, then since the mover is in it, it is clear that the mover and that which is moved will be together, and there will be no intermediary between them.
That which is moved by another is moved in one of four ways. The motions which are from another are four: pushing, pulling, carrying, and twirling. For all the others are reduced to these.
Pushing is either pushing on or pushing off. Pushing on occurs when the mover does not leave that which is moved. Pushing off occurs when the pusher leaves.
Carrying will be in the three other motions. For that which is carried is not moved in itself but accidentally. For in this that which is moved is either in that which is moved or is on that which is moved. The carrier is moved either by a pushing or a pulling or else it is led on by a twirling. Therefore it is clear that carrying will be in these three motions.
Pulling occurs when there is a faster motion of the puller either to itself or to another, not separated from that which is pulled. For pulling occurs both to itself and to another. Other pullings that are the same in species are reduced to these, for example, inhaling and exhaling, and spitting, and whatever bodies are emitted or received, and spathesis, and kerkisis. Gathering of things is one thing and separating is another. Therefore all motion in respect to place is a gathering or a separating.
Twirling is composed of pushing and pulling. For the mover pushes this and pulls that.
Therefore it is clear that if the pusher and the puller are together with that which is pushed and pulled, there is no intermediate between that which is moved and the mover.
This is clear from what was said. Pushing is motion either from itself or from another to another. But pulling is from another to itself or to another. Thus far there is coming together and going apart.
There is throwing when there occurs a faster motion than that which is borne according to nature, a stronger pushing having been made. This being done, it is borne as long as the motion of that which is borne is stronger. Therefore it is clear that the mover and that which is moved are together, and there is no intermediary between them.
897. In the previous demonstration, the Philosopher had assumed that a mover is continuous, or at least contiguous, with the mobile. This he now intends to prove. First, he proves his proposition; second, he proves something he had assumed in his proof, at “all things that are altered” (245b19; [913]). About the first, he does two things: first, he states his intention; second, he proves his proposition, at since there are three (243a6; [898]).
He says first (243a32) that mover and moved are together.
But something is said to be moved in two senses.
One sense is as the end moves the agent, and such a mover is sometimes distant from the agent it moves;
The other sense is as that moves that is the actual beginner of the motion.
It is of this latter that Aristotle speaks, and that is why he adds not as the cause for the sake of which, but as the principle of motion.
Again, a mover as principle of motion can be immediate or remote. Aristotle speaks of what causes motion immediately and calls it the first mover, which refers not to what is first in the series of movers, but to a mover that is immediate to the mobile.
And, because he had in book 5 said that things in the same place are together, one might conclude from that and from the statement that mover and moved are together that, when one body is moved by another, they must both be in the same place. Therefore, to prevent this misunderstanding, he adds that together is not taken here in the sense of being in the same place, but in the sense that nothing is intermediate between the mover and the moved. It is in this sense that things in contact, or things that are continuous, are together, because their extremities are together or are one and the same.
And the fact that he proceeded in the previous demonstration solely along the line of local motion does not mean that his proposition is true only in cases of local motion. Therefore, to exclude this possible misunderstanding, he adds that the statement that mover and moved are together must be taken in a sense common to all motions, for it is found in every kind of motion that mover and moved are together in the sense explained.
898. Then, at “and since there are three” (243a6), he proves his proposition. About this, he does two things: first, he enumerates the species of motion; second, he proves his proposition for each kind, at “whatever is moved is moved” (243a21; [899]).
He therefore says first (243a6) that there are three kinds of motion: one is in respect to place, called local motion; one is in respect of quantity, called growth and decrease; the third is in respect of quality, called alteration.
He makes no mention of generation and ceasing to be because they are not motions, as was explained in book 5. However, since generation and ceasing to be are the termini of a motion, that is, of alteration, as was proved in book 6, then, if he proves his proposition in regard to alteration, it will also be proved in regard to generation and ceasing to be.
Now, just as there are three kinds of motion, so there are three kinds of mobile and also three kinds of mover. And, in all, it is true that the mover and the moved are together, as will be shown for each case. But first it must be proved for local motion, which is the first of motions, as will be shown in book 8.
899. Then, at “whatever is moved is moved” (243a21), he proves his proposition for each kind of motion: first, in local motion; second, in the motion of alteration, at “neither is there an intermediary” (244a25; [909]); third, in the motion of growth and decrease, at “and that which is increased” (245a26; [912]). About the first, he does two things: first, he shows the proposition in cases that are evident; second, in less evident cases, at “that which is moved by another” (243a23; [900]).
He says first (243a21) that we must say that whatever is being moved in respect of place is moved either by itself or by something else.
To say that something is moved by itself can be taken in two senses: first, by reason of the parts, as when we shall prove in book 8 that, in things that move themselves, one part moves and another part is moved; second, first and per se—that is, such that the whole moves itself according to itself and as a whole, as when he proved earlier that nothing moves itself in this way.
But, if it be granted that something is moved by itself in both ways, it is clear that the mover will be in what is being moved either in the way that a thing is itself, or as a part is in a whole, as a soul is in an animal. Thus, it will follow that the mover and the moved are together in such a way that nothing exists between them.
900. Then, at “that which is moved by another” (243a23), he proves the same in those cases where it is less evident, in regard to things that are moved according to place by something else. About this, he does three things: first, he distinguishes the ways in which something happens to be moved by something else; second, he reduces these ways to two ways, at “therefore it is clear that if the pusher” (244a17; [906]); third, he proves his proposition for these two ways, at “this is clear from what” (244a19; [907]). About the first, he does two things: first, he divides the ways in which something is moved by something else into four: pushing, pulling, carrying, and twirling. For all motions that are caused by something distinct from the moved are reduced to these four.
901. Second, he explains these four ways, at “pushing is either pushing on” (243a26).
First, he explains pushing as that which occurs when the mover makes a mobile be distant from him by moving it. Pushing is of two kinds: pushing on and pushing off.
Pushing on occurs when the mover pushes a mobile but does not desert it, but rather accompanies it to the place it is going.
Pushing off occurs when the mover moves a mobile in such a way that it deserts it and does not accompany it to the very end of the motion.
902. Then, at “carrying will be in the three” (243a28), he explains carrying as a motion based on three other motions: pushing, pulling, and twirling, in the same way that what is per accidens is based on what is per se. For that which is carried is not moved per se, but per accidens, inasmuch as something in which it exists is being moved (as, for example, when someone is carried by a ship on which he is, or carried by a horse upon which he is). That which carries is moved per se, since one does not proceed to infinity in things that are moved per accidens. And, thus, the first carrying thing is moved per se on account of some motion that is either a push or a pull or a twirl. From this, it is clear that carrying is contained in the other three motions.
903. Then, at “pulling occurs when there is” (243b23), he explains the third way, pulling. And note that pulling differs from pushing: in the latter, the mover is related to the mobile as the terminus from which of its motion, but in pulling he is related as the terminus to which. Therefore, only what moves something to itself is said to pull.
However, the act of moving something to oneself in respect of place occurs in three ways.
First is the way that an end moves, that is, in the sense in which the poets declare that the end is said to pull, when they say that one’s own desire pulls him. It is in this sense that a place may be said to pull what is naturally moved to a place.
In a second way, something is said to pull something else when it moves it to itself by altering it somehow, such that the altered object is moved in respect of place as a result. It is in this way that a magnet is said to pull iron. For just as the generator of a thing moves heavy and light things inasmuch as it gives them the form through which they are moved to their place, so the magnet confers some quality on the iron by which it is moved toward the magnet.
That this is true he makes clear by three facts.
First, a magnet does not draw iron from just any distance, but within a certain limit of nearness. But, if the iron were moved to the magnet only as to an end in the way that a heavy body is moved to its place, it should do so no matter how great the distance they are separated by.
Second, if the magnet be covered with oil, it cannot draw the iron, because the oil impedes the altering quality or modifies it.
Third, in order that a magnet attract iron, the iron must first be rubbed by the magnet, especially if the magnet is weak. It is as though the iron receives from the magnet some power by which it is moved toward it. Thus, a magnet pulls the iron not only as an end, but as a moving cause and as an altering cause.
In a third way, something is said to pull something else because it moves it to itself in respect of local motion only. And it is in this sense that Aristotle here defines pulling, that is, in the sense that one body pulls another in such a way that the puller accompanies what it pulls.
904. This, therefore, is what he says: pulling occurs when there is a faster motion of the puller either to itself or to another, not separated from that which is pulled. And he says, either to itself or to another, because a voluntary mover can use something else just as itself; hence, such a mover can both push something from something else as from itself and pull something toward something else as toward itself. However, this does not happen in natural motions, where a natural push is always away from the pusher and a natural pull is toward the puller.
He said, when there is a faster motion, because sometimes what is pulled is also being moved toward its objective by its own motion but is compelled by the puller to move with a swifter motion. And, since the puller acts by its own motion, the motion of the puller must be swifter than the natural motion of what is being pulled.
The reason for saying, not separated from that which is pulled, is to distinguish it from a push. For in some pushes, the pusher separates itself from the object pushed, and in some not, but the puller is never separated from what is pulled; indeed, both the puller and the pulled are moved at once.
Finally, he said, to itself or to another, because a pull can be toward the puller or toward something else, as was explained for voluntary motions.
905. Since there are motions in which the presence of a pull is not clearly evident, he shows that even those are reduced to the types mentioned, that is, that they are directed toward the puller or toward something else. And this is what he says, namely, that all other types of pulling that are not called a “pull” are reduced to these two types, because they are specifically the same as one or the other of these two, insofar as a motion derives its species from its terminus—for the motions he has in mind are either toward the puller or toward something else, as is evident in inhaling and exhaling. For inhaling is pulling air in, and exhaling is pushing it out; likewise, spitting is the pushing out of spittle. The same is to be said of all those other motions by which bodies are expelled or drawn inward, because emitted is reduced to pushing out and received to pulling.
In like manner, spathesis is a type of pushing and kerkisis is a type of pulling. The former comes from the Greek word for sword, and hence spathesis is to cut with a sword, which is done by pushing. And, therefore, the other text that says speculation seems to be corrupt through the fault of the transcriber, because for spathatio he has written speculatio.
Kerkisis, however, is from the Greek word kerkis, which refers to a weaver’s tool that he pulls toward himself as he weaves, called in Latin radius (hence another text has radiatio).
These two motions, and indeed all cases of emitting or receiving are either a gathering, which pertains to drawing toward (the gatherer being one who moves things together), or a separating, a separator being one who pushes, for a push is a motion of one thing from another. In this way, it is clear that all local motion is either a gathering or a scattering, because every local motion is either from something or toward something. Consequently, all local motion is either a pushing or a pulling.
906. Then, at “twirling is composed of pushing” (243b29), he explains twirling as a motion composed of a pull and a push, for when something is twirled, it is on the one hand pushed, and on the other being pulled.
Then, at “therefore it is clear” (244a17), he shows that the four general ways are reduced to pushing or pulling and that whatever can be said of all four is contained in these two. For since carrying consists of the other three, and twirling is composed of a push and a pull, what remains is that every local motion caused by a mover is reduced either to a push or a pull. Hence, it is evident that, if the mover and moved are together in the motions of pulling and of pushing such that the pusher is together with what is being pushed and the puller with what is being pulled, then it is universally true that there is nothing between the mover and what is moved in respect of place.
907. Then, at “this is clear from what was said” (244a19), he proves his proposition for these two motions.
First, he presents two arguments that prove the proposition;
second, he answers an objection, at “there is throwing when” (244a21; [908]).
The first argument is based on the definition of the two motions. For a push is a motion from the mover or from something into something else; consequently, at the beginning of the motion, the pusher must be together with what is being pushed, at least when the pusher removes the object that is being pushed from himself or from something else. A pull, however, is a motion toward the puller or toward something else, as we have said—a motion, I say, in which the puller is not separated from what is being pulled. Hence, it is clear that, in these two motions, the mover and the moved are together.
The second argument is based on gathering and scattering. For it was said above that pushing is scattering and pulling is gathering. And he says that, thus far, there is coming together, that is, combination, and pulling apart, that is, division. Now, no one gathers or scatters without being present to the things he is gathering or scattering. Therefore, it is clear that, in pulling and in pushing, the mover and the moved are together.
908. Then, at “there is throwing when” (244a21), he answers an objection that could be lodged against the push. For it was said of pulling that the motion of the puller is not separated from what is being pulled. But it was said that, in pushing, the pusher is in certain cases removed from the object pushed. Such a case of pushing is called throwing, which occurs when something is pushed with some force into the distance. Hence, it seems that, in this case, the mover and the moved are not together.
To answer this, he says that throwing occurs when the motion of what is thrown becomes faster than its natural motion on account of a strong impulse. For when something is thrown by a strong push, the air is moved with a motion swifter than its natural motion, and with air’s motion, the thrown body is carried along. And so, as long as the air stays pushed, so long does the thrown object remain in motion. This is what Aristotle says, that when such a push is made, the thrown object remains in motion as long as a motion stronger than its natural motion remains in the air.
Thus, with this objection answered, he concludes that the mover and the moved are together, and that nothing intervenes between the two.