LECTURE 23 (267 a 22-b 26)

THE FIRST MOVER CANNOT HAVE MAGNITUDE

1164. From the solution of the difficulty which he raised concerning the motion of throwing, he has concluded that a motion caused by many movers is not one and continuous. Here he proceeds to his main point, namely, he proves the unity of the first mover.

             Concerning this he makes two points. First he proves his position. Secondly, where he says, 'There is a further difficulty . . .' (267 b 9), he raises a difficulty and answers it.

             Concerning the first part he makes three points. First he proves the unity of the first mover from the continuity of motion. Secondly, where he says, '. . . if, then, it is in motion . . .' (267 a 25), he explains how continuous motion proceeds from one mover. Thirdly, where he says, 'Moreover the movent . . .' (267 b 6), he shows where the source of continuous motion is.

             1165. He proves from the continuity of motion that there must be one mover by beginning with what he has proven above, namely, there must be a motion which is eternally continuous. Continuous motion, moreover, is one, as was established in Book V. Therefore, some one motion must always exist. But in order for this motion to be one, it must be the motion of one moved magnitude (for it was established in Book VI that what is indivisible cannot be moved). Furthermore, this motion must be caused by one mover. For if there are diverse mobile objects or diverse movers, there will not be one motion, and consequently, not a continuous motion. Rather one motion will be divided from another because of a division of the mobile object or the mover, and these motions will be related consecutively. Therefore, there must be one mover, which either moves and is moved or which moves and is immobile.

             1166. Next where he says, '. . . if, then, it is in motion . . .' (267 a 25), he shows how there can be continuous motion from one mover.

             Concerning this he makes two points. First he shows how there can be eternally continuous motion from one mover. Secondly, where he says, '. . . and this motion alone . . .' (267 b 4), he shows how this motion is regular.

             He says, therefore, first that one motion which is from one mover is from either a moved or an unmoved mover, as was said. If it is a moved mover, it follows that it is moved by another, according to what has been proven above. But this cannot proceed to infinity, as was established above, for this order of movers and mobile objects will end and will arrive at some first mobile object which is moved by an immobile mover, which has no necessity to move because it is not moved by another. For that which is moved by another must move insofar as necessity is placed in it by its mover. And since it is changed from its disposition, it cannot always move uniformly because its disposition varies.

             But no necessity is imparted by another to an unmoved mover, and its disposition does not change. Hence it does not move from necessity but rather can always move. For that which moves without being changed itself, moves without fatigue. Some movers become fatigued in moving because they are also simultaneously moved. And because of this fatigue they cannot move forever. Hence it follows that an unmoved mover can move with an eternally continuous motion.

             1167. And since, as was said in Book V, regularity and uniformity are required for the perfect continuity and unity of motion, as a result, where he says, '. . . and this motion alone . . .' (267 b 4), he shows that motion from an immobile mover is regular.

             He says that either only the motion from an immobile mover is regular, or, if other motions are regular, this is the most regular. He makes this distinction because the disposition of a moved mover sometimes remains the same and does not vary for some period of time, at least with respect to sensation. And accordingly it seems to move for some time with a regular motion. But that which is always unmoved causes the most regular motion, for such a mover undergoes no change at all. He says this in order to show that there are certain movers which are not moved by the motion by which they move. For example, a celestial body is not moved by the motion of alteration, but by another motion, namely, local motion. But the first, absolutely immobile mover is moved in no way.

             In order for motion to be regular and uniform, not only is it necessary that the mover be absolutely immobile, but the motion must also be uniform such that that which is moved does not have another change joined to that by which it is moved by the immobile mover, just as the local motion of a celestial body is caused by an immobile mover, and no other change is joined to it. For, if it were altered, the same disposition for motion would not always remain in it, and thus the motion would not be uniform.

             1168. Next where he says, 'Moreover the movent . . .' (267 b 6), he shows where the source of the first continuous motion is. Since it has been shown that the first motion is circular, which motion pertains to a circular magnitude, the first source of this motion must be in the middle, that is, in the centre, or in the circumference, for these are the sources of a circular magnitude. For in a circular magnitude, lines are drawn from the centre to the circumference, and so one of these must be taken as the source and the other as the terminus.

             He proves as follows that the source of the first motion is in the circumference. The closer any motion is to the source of its motion, the faster is its velocity because it receives a greater impression from the mover. But in the motion of the entire firmament, which is due to the first immobile mover, we see that the closer a mobile object is to the outermost circumference, the faster is its motion. Therefore, the mover is in the circumference, and not in the centre.

             The major premise of this argument is clear. But to clarify the minor premise, we must realize that a double motion is found in celestial bodies. One is the motion of the whole firmament by which the whole firmament is rotated from east to west in daily motion. This is the first motion. The other motion is the one by which the stars are moved conversely from west to east.

             In this second motion, the closer that each celestial body is to the centre, the faster is its motion, as is clear from the computations of the astronomers, who compute the time of the Moon's motion as one month; that of the Sun, Mercury, and Venus as one year; that of Mars, two years; Jupiter, 10; Saturn, 30; and of the fixed stars 36 thousand years.

             But the motion of the whole firmament is just the opposite. For the further a celestial body is from the earth, the faster is its motion, since it traverses a greater magnitude in the same time. For the circumference of circles are greater the more distant they are from the centre. And all celestial bodies are rotated in the same time with respect to the motion of the whole. And so the higher body must be the faster. Hence it follows that the source of the first motion is not in the centre but in the circumference.

             1169. But a problem arises concerning this conclusion. For the first mover, as he concludes below, is indivisible and has no magnitude and its power is not a power which resides in a magnitude. But such a being does not seem to have a determined location in a body. Therefore, it is not proper for the first mover to be in one part of the first mobile object rather than another.

             But it must be stated that the first mover is not said to be in some part of its mobile object through a determination of its own substance, but through its power of motion. For it begins to move from some part of its mobile object, and therefore it is said to be in the heavens rather than in earth, and preferably in the east where it begins to move. This cannot be understood in the sense that the first mover is fixed to some determinate part of its mobile object. For no determinate part of the mobile object is always in the east. Rather that part which is now in the east is later in the west. And so it is clear that its motive power is said to be in the east because of the influence of its motion, and not because of a determination of its substance.

             With respect to the motion of the spheres it must be realized that they have a certain immobility as well as motion. For the parts are moved by changing place both in the subject and in reason [ratio]. But the whole is moved by changing place only in reason [ratio] and not in subject, as was established in Book VI. And these two are attributed to the two principles of spherical magnitude which were mentioned here. For the source of motion is in the circumference; but the source of immobility is in the fixed centre.

             1170. Next where he says, 'There is a further difficulty . . .' (267 b 9), he raises a difficulty about the foregoing. First he raises the difficulty and secondly he answers it, where he says, 'Such a movement must . . .' (267 b 11).

             He has said above that an immobile mover can cause continuous motion, and so here he asks whether a moved mover can cause continuous motion--really continuous motion, that is, without any such interruption as occurs when someone pushes a body, which is pushed again by another. It is clear that this motion, which is continued in respect to the mobile object, is not really continuous, because the motions are not continuous. Rather one motion is consecutive to the other. For this is not a continuous pushing, rather there is an interruption such that a pushing follows a pushing.

             1171. Next where he says, 'Such a movent must . . .' (267 b 11), he answers the above difficulty and shows that no moved mover can cause continuous motion.

             It must be said that a mobile object which seems to be moved continuously either is moved immediately through the whole motion by that moved mover itself, or else by many intermediaries, one of which is contacted by another, as was said of the motion of throwing. This distinction applies whether the moved mover moves by pushing or by pulling or by both motions, as occurs in the motion of spinning, as was shown above in Book VII. Nor are there many ways in which a thing is moved locally by a moved mover per se and not per accidens (for what is carried is moved per accidens).

             And he has said in reference to things which are thrown that there are different movers. But this seems to be false, because a thrown body seems to be moved continuously by one existing air. In order to reject this, he adds that since air or water is readily divisible, different movers move the object. And they always move as long as the motion of the thrown body endures. And although the air seems to be one, nevertheless, it is many by division.

             In both cases, however, that is, whether the moved mover moves by pushing or by pulling, there cannot be one motion. Rather there are consecutive motions because of the explanation given above for the motion of throwing, namely, there are many movers.

             It follows, therefore, that only motion from an immobile mover can be eternally continuous. For this mover is always related in the same way with respect to the same disposition in itself. And therefore it can always and continuously be related in the same way to the mobile object so that it always moves it with uniformity.

             It should be noted, moreover, that the Philosopher here attributes the eternity of continuous motion to the immobility of the mover, but above to its infinite power. For if the eternity of continuous motion is taken with respect to the repetition of motion, it is due to the immobility of the mover. For if the mover always maintains the same relation, it can always repeat the same motion. But the infinite power of the mover is related to the entire eternity or per se infinity of the motion, as was said above.

             And it is also to be noted that since no moved mover can cause eternally continuous motion, in Metaphysics, XII, he intends to prove a multitude of immobile movers corresponding to the multitude of celestial motions, as if that consideration follows from this one.

             1172. Next where he says, 'Now that these points . . .' (267 b 18), he concludes to his main point from what was demonstrated above.

             He says that from the above it is clear that it is impossible for the first immobile mover to have any magnitude, either in the sense that it is a body or in the sense that it is a power in a body. For if it has magnitude, that magnitude is either finite or infinite. But it was shown above in Book III in discussing the common properties of nature that an infinite magnitude is impossible. It follows, then, that if it has magnitude, that magnitude is finite. But it can be proven that it does not have a finite magnitude because it is impossible for a finite magnitude to have infinite power. The first immobile mover, however, must have infinite power. Therefore it cannot have a finite magnitude.

             He proves that the first immobile mover must have infinite power from what was demonstrated above, namely, it is impossible for some thing to be moved in an infinite time by a finite power. But the first mover causes eternal and continuous motion and exists as one and the same in infinite time. Otherwise, that motion would not be continuous. Therefore, it has infinite power. And thus it does not have finite magnitude. And an infinite magnitude cannot exist. It is clear, therefore, that the first mover is indivisible, both because it has no parts (as is also true of an indivisible point) and because it has absolutely no magnitude, existing, as it were, outside of the genus of magnitude.

             And thus the Philosopher ends his general discussion of natural things with the first principle of the whole of nature, who is over all things, God, blessed forever, Amen.