Lecture 13 — The first mover is eternal and immobile, while the first motion is eternal

Moreover, a conviction that there is a first unmoved something may be reached not only from the foregoing arguments, but also by considering again the principles operative in movers.

Now, it is evident that, among existing things, there are some that are sometimes in motion and sometimes at rest.

This fact has served above to make it clear that it is not true either that all things are in motion or that all things are at rest or that some things are always at rest and the remainder always in motion. On this matter, proof is supplied by things that fluctuate between the two and have the capacity of being sometimes in motion and sometimes at rest.

The existence of things of this kind is clear to all, but we wish to explain also the nature of each of the other two kinds and show that there are some things that are always unmoved and some things that are always in motion.

In the course of our argument directed to this end, we established the fact that everything that is in motion is moved by something, and that the mover is either unmoved or in motion, and that, if it is in motion, it is moved either by itself or by something else and so on throughout the series;

and so we proceeded to the position that the first principle that directly causes things that are in motion to be moved is that which moves itself, and the first principle of the whole series is the unmoved.

Further, it is evident from actual observation that there are things that have the characteristic of moving themselves, such as the animal kingdom and the whole class of living things.

This being so, then, the view was suggested that perhaps it may be possible for motion to come to be in a thing without having been in existence at all before, because we see this actually occurring in animals: they are unmoved at one time and then again they are in motion, as it seems.

We must grasp the fact, therefore, that animals move themselves only with one kind of motion, and that this is not strictly originated by them.

The cause of it is not derived from the animal itself, it is connected with other natural motions in animals, which they do not experience through their own instrumentality, such as increase, decrease, and respiration.

These are experienced by every animal while it is at rest and not in motion in respect of the motion set up by its own agency; here the motion is caused by the atmosphere and by many things that enter into the animal.

Thus, in some cases, the cause is nourishment: when it is being digested, animals sleep, and when it is being distributed through the system, they awake and move themselves, the first principle of this motion being thus originally derived from outside.

Therefore, animals are not always in continuous motion by their own agency: it is something else that moves them, itself being in motion and changing as it comes into relation with each several thing that moves itself.

(Moreover, in all these self-moving things, the first mover and cause of their self-motion is itself moved by itself, though in an accidental sense—that is to say, the body changes its place, such that what is in the body changes its place also and is a self-mover through its exercise of leverage.)

Hence we may confidently conclude that, if a thing belongs to the class of unmoved movers that are also themselves moved accidentally, it is impossible that it should cause continuous motion.

So, the necessity that there should be motion continuously requires that there should be a first mover that is unmoved even accidentally, if, as we have said, there is to be in the world of things an unceasing and undying motion and the world is to remain permanently self-contained and within the same limits. For if the first principle is permanent, the universe must also be permanent, since it is continuous with the first principle.

We must distinguish, however, between accidental motion of a thing by itself and such motion by something else, the former being confined to perishable things, whereas the other case belongs also to certain first principles of heavenly bodies—of all those, that is to say, that experience more than one locomotion.

And, further, if there is always something of this nature—a mover that is itself unmoved and eternal—then that which is first moved by it must be eternal.

Indeed, this is clear also from the consideration that there would otherwise be no generation and corruption and no change of any kind in other things, which require something that is in motion to move them. For the motion imparted by the unmoved will always be imparted in the same way and be one and the same, since the unmoved does not itself change in relation to that which is moved by it.

But what is moved by something that, though it is in motion, is moved directly by the unmoved stands in varying relations to the things that it moves, such that the motion that it causes will not be always the same: by reason of the fact that it has contrary positions or forms at different times, it will produce contrary motions in each several thing that it moves and will cause it to be at one time at rest and at another time in motion.

The foregoing argument, then, has served to clear up the point about which we raised a difficulty at the outset—why is it that, instead of all things being either in motion or at rest, or some things being always in motion and the remainder always at rest, there are things that are sometimes in motion and sometimes not?

The cause of this is now plain: it is that, while some things are moved by an eternal unmoved mover and are therefore always in motion, other things are moved by a mover that is in motion and changing, such that they too must change.

But the unmoved mover, as has been said, since it remains permanently simple and unvarying and in the same state, will cause motion that is one and simple.

1077. After showing that the first mover is perpetual and utterly immobile on account of the perpetuity of the generation and corruption of animals, which move themselves, the Philosopher now intends to prove the same with an argument based on the moving principles.

About this, he does three things:

first, he reviews things said from the beginning of this treatise;

second, from these, he forms an argument for his proposition, at hence we may confidently (259b20; [1081]);

third, he finishes the solution of a doubt mentioned above, at the foregoing argument (260a11; [1085]).

1078. About the first, he reviews three things.

First (259a21), he reviews the destruction of certain improbable positions. And he says that anyone can know that there is a first immobile mover not only from the foregoing, but also by considering the principles of motion. And, as was said above, it is evident to sense that, among natural things, some are found that are at one time being moved and at another time at rest. (Lect. 6, n. 1014.)

From this, it was explained above (Lect. 5, n. 1005ff.; lect. 6, nn. 1014–15.) that none of these three positions is true:

the position that all things are always being moved;

the position that all things are always at rest;

and the position that all things that rest always rest, and that those being moved are always being moved.

The truth of this matter is demonstrated by the very things found under both—namely, under motion and under rest—since they have the potency to be moved at one time and to be at rest at another.

1079. Second, he recalls the process he went through (Lect. 7ff.) when investigating the first immobile mover, at the existence of things (259a27). And he says that, because things that at one time are being moved and at another time are at rest are plain to all, lest anyone follow a fourth position (Cf. lect. 5, n. 1005.)—saying that all beings are such that they are at one time being moved and at another time at rest—we want to demonstrate two differing natures by showing that there are certain things that are always immobile and certain things, again, that are always being moved.

And, in dealing with this matter, we proposed first that whatever is being moved is being moved by something, (Lect. 7, n. 1021.) and that this thing by which something is being moved is either immobile or is itself being moved, and if it is being moved, then it is moved either by itself or by another. (Lect. 9ff.) And, since one cannot proceed to infinity in the series of being moved by another, we must come to this: there is some first principle of motion such that, in the genus of things that are moved, there is a first principle that moves itself, and beyond that, absolutely among all, there is a first principle that is immobile. Nor ought it to be thought strange that something move itself, because we plainly see many such in the genus of living things and animals.

1080. Third, at this being so (259b3), he recalls an objection mentioned and solved above. (Lect. 4, nn. 999, 1002.) For since he had proved the eternity of motion, he cited to the contrary an objection based on living things that, after having been at rest, begin at a certain time to be moved. And what he says here is that those living things that move themselves seem to foster the opinion that, in the entire universe, motion begins after previously not having been, on the ground that we see this happen in things, namely, that they at one time begin to be moved, when previously they were not being moved.

To solve this, it is necessary to accept that animals move themselves with respect to one motion, namely, local motion, for only this motion, based on appetite, is found in animals. And yet animals do not properly move themselves even with respect to this motion as though another cause of this motion does not preexist. For no animal is of itself the first cause of being moved locally, but other motions precede—not voluntary but natural—either from within or from without, according to which the animals do not move themselves, as is plain in the motions of growth and decrease, and respiration, according to which animals are moved even though they rest with respect to local motion, by which they are moved by themselves.

The cause of these local motions is either an extrinsic container—namely, the heavens and air—by which the bodies of animals are changed externally, or is something that enters the bodies of animals, as air enters through breathing and as food enters through eating and drinking.

And, from such changes, caused either from within or from without, it happens that animals at a certain time begin to be moved, when previously they were not being moved, as is plain from the change that arises from food, for while the food is undergoing heat, the animals sleep on account of the vapors being broken down, but when the food is now digested and dissolved, and the vapors are left, the animals awaken and get up and move themselves from place to place. In all this, nevertheless, the first principle of motion is something extrinsic to the nature of the animal that moves itself.

That is the reason that animals are not always moved by themselves, for with respect to any animal moving itself, there is found some previous mover that is being moved and causes motion. For if it were entirely immobile, it would always maintain itself in the same way in causing motion, and consequently, the motion also of the animal would be perpetual. But, because this extrinsic mover that moves animals is itself moved, it does not always move in the same way.

Hence, neither do animals always move themselves in the same way, for in all these things, the first mover that is the cause of the animal’s moving itself, such as the soul, causes motion in such a way that it is itself being moved not per se, but per accidens, for the body is changed with respect to place, and when the body has been changed, that which exists in the body, namely, the soul, is also changed per accidens. And, thus, the whole that moves itself is changed of necessity, such that it does not maintain itself in the same disposition for causing motion.

1081. Then, at hence, we may confidently (259b20), he proves his proposition from the foregoing.

First, he proves that the first mover is immobile;

second, that the first motion is perpetual, at and, further, if there (259b32; [1083]).

About the first, he does two things:

first, he proves the proposition;

second, he dismisses an objection, at we must distinguish (259b28; [1082]).

He says first (259b20) that, from the foregoing, we can know that, if some principle is an immobile mover nevertheless moved per accidens, it cannot cause a continuous and perpetual motion. For the reason assigned for saying that animals do not always move is that they are moved per accidens. But it has been shown above that the motion of the universe must be continuous and perpetual. (Lect. 1ff.) Therefore, it is necessary that the first moving cause in the whole universe be immobile in such a way as not to be moved even per accidens.

But, as was said above, (Lect. 1, n. 966.) a motion that is immortal and unceasing ought to be found in natural things, and the whole being, that is, the disposition of this universe, should be maintained in its disposition and in the same state. For from the immobility of the principle that is posited as remaining immobile, it follows that the entire universe has an eternal permanence, insofar as it is joined to the first immobile principle and receives an influence from it.

1082. Then, at we must distinguish (259b28), he excludes an objection. For he had said that, if a mover is moved per accidens, it does not move with a sempiternal motion. Now, this seems to give rise to an objection, because, according to his position, the motions of the inferior orbs (such as the sun and moon and other planets) are eternal, and yet their movers seem to be moved per accidens, if we follow what he had just said. For he said that the reason that the soul of an animal is moved per accidens is that the animal’s body is moved by an external principle, which is not from the soul. In like manner, it appears that the orb of the sun is moved by some other motion as though carried along by the motion of the first orb, insofar as it revolves from east to west; this is not the way it is moved by its proper mover, but contrariwise, from west to east.

He dismisses this objection, saying that being moved per accidens can be attributed to something either with respect to itself or with respect to something else, and this is not the same. Now, being moved per accidens can be attributed to the movers of the orbs of the planets not in the sense that these movers are moved per accidens, but that the orbs moved by them are moved per accidens in being influenced by the motion of the superior orb. And this is what he says: to be moved per accidens by something else is attributed to certain principles of heavenly motions in the case of the movers of the orbs that are moved by more than one motion, namely, by their own and by that of the superior orb.

But the other case—namely, that a thing be moved per accidens with respect to itself—is found only in perishable things, as in the souls of animals. The reason for this diversity is that the movers of the superior orbs are not made to exist through being united to bodies, and their connection with the latter is unvarying; therefore, although the bodies of the orbs are moved, the motors are not moved per accidens. But the souls that move animals depend for their existence on being united to their bodies, and they are connected in a way subject to variation, and accordingly, as the bodies are affected by change, the souls themselves are said to be changed per accidens.

1083. Then, at and, further, if there (259b32), he proves that the first motion is perpetual. And he does this with two arguments, the first of which depends on the foregoing. A motion that is not perpetual is found to be from a mover that is moved per se or per accidens, as is evident from above. Since, therefore, the first mover is immobile and perpetual, and is moved neither per se nor per accidens, then, necessarily, the first mobile, which is moved by this utterly immobile mover, is moved with a perpetual motion.

Now, it should be noted that he above proved the immobility of the first mover by means of the perpetuity of motion, shown above. (Lect. 1ff.) Here, on the contrary, through the immobility of the first mover, he proves the perpetuity of motion. But this would be arguing in a circle if the same motion were meant in both arguments.

Hence, it must be said that, above, he proves the immobility of the first mover from the perpetuity of motion in general; that is why he said that, among the things that exist, there is an unceasing and immortal motion. But here, through the immobility of the first mover he proves the perpetuity of the first motion. From this, it is plain that what the Commentator says is false, namely, that, in the beginning of book 8, Aristotle proved that the first motion is perpetual. (Cf. lect. 1, n. 966.)

1084. The second argument is given at indeed, this is clear also (260a1), and it is taken from the perpetuity of generation. And he says that the first motion is perpetual for another reason, namely, that the only way temporal generation and ceasing to be and changes of this sort can exist is that something move and be moved, for it has been proved above that every change is caused by some mover. (Lect. 7–8.) Therefore, coming to be and ceasing to be and change of this kind ought to be from a mover. But they cannot be immediately from the immobile mover, because the immobile will always cause the same motion and in the same way, for its relation to the mobile is not variable; and, given a relation between mover and moved that remains the same, the motion remains always the same. However, coming to be and ceasing to be are not always in the same state, but at one time something is generated and at another it ceases to be. Therefore, these changes are not immediately from the immobile mover, but from a mobile mover.

Now, whatever is moved by a moved mover that in turn is moved by the immobile mover can retain perpetuity in spite of the alternation of diverse motions, because, since the mobile mover stands in varying relation to the things moved, it will not always cause the same motion. Rather, since it occupies differing positions (if moved with local motion), or assumes differing forms (if moved with a motion of alteration), it will produce a contrary motion in other things and will cause them to be at one time at rest and at another time in motion. He says contrary positions or forms because it has not yet been proved by what form of motion the first mobile is moved; but he will inquire into this later. (Lect. 19–20.)

Thus, therefore, insofar as it is moved, it is a cause of the diversity of motions; but insofar as it is moved by the immobile mover, it is the cause of the perpetuity in this diversity of changes. Therefore, the very perpetuity of generation shows that the first motion is perpetual and brought about by the immobile mover.

But it should be understood that these arguments by which Aristotle tries to prove that the first motion is perpetual do not conclude of necessity, for it can happen without any change in the first mover that it not always cause motion, as was shown above in the beginning of this book 8. (Lect. 2, n. 988ff.)

1085. Then, at the foregoing argument (260a11), he draws a conclusion that he left unsettled above, (Lect. 5, n. 1005.) namely, why some things are always in motion and some not always. And he says that the cause of this is now plain from what has gone before. Things that are moved by an immobile and eternal mover are always in motion; things that are moved by a changed mover are not always in motion—for the immobile, as previously stated, since it remains absolutely alike and in the same state, will cause a motion that is one and simple.