LECTURE 1 (224 a 21-b 34)

MOTION PER SE IS DISTINGUISHED FROM MOTION PER ACCIDENS. ONLY MOTION PER SE MUST BE TREATED

             638. After the Philosopher has treated motion and those things which follow upon motion in general, he proceeds here to the division of motion.

             This discussion is divided into two parts. First he divides motion into its species. Secondly, in Book VI where he says, 'Now if the terms . . .' (231 a 21), he divides motion into its quantitative parts.

             The first part is divided into two parts. First he divides motion into its species. Secondly, where he says, 'Let us now proceed . . .' (226 b 19), he treats the unity and opposition of motion.

             The first part is divided into two parts. First he distinguishes motion per se from motion per accidens. Secondly, where he says, 'And since every change . . .' (224 b 35), he divides motion per se into its species.

             The first part is divided into two parts. First he distinguishes motion per se from motion per accidens. Secondly, where he says, 'Now accidental change . . .' (224 b 27), he teaches that motion per accidens must be omitted, but motion per se must be treated.

             Concerning the first part he makes two points. First he distinguishes motion per se from motion per accidens. Secondly, where he says, 'It is now clear . . .' (224 b 22), he summarizes his conclusions.

             In the first part he distinguishes motion per se from motion per accidens in three ways. He does this first in respect to the mobile object; secondly, in respect to the mover, where he says, 'And there are the same . . .' (224 a 31); and thirdly, in respect to the terminus, where he says, 'We have, then, the following . . .' (224 a 33).

             639. He says, therefore, first that whatever is changed is said to be changed in three ways.

             First, a thing is said to be changed per accidens, as when we say that the musician walks. For it is accidental that this man who walks is a musician.

             Secondly, a thing is said to be changed simply because one of its parts is changed, for example, all things which are said to be changed in respect of their parts. He gives an example of alteration. The animal body is said to be healed because the eye or the chest, which are parts of the whole body, is healed.

             Thirdly, a thing is said to be moved neither per accidens nor in respect to a part. Rather it itself is moved primarily and per se. He says 'primarily' to exclude motion in respect to a part. And he says 'per se' to exclude motion per accidens. Furthermore, the per se mobile object varies according to the diverse species of motion. Thus an alterable object is mobile in respect to alteration. And an augmentable object is mobile in respect to increase. And within the species of alteration a curable object, which is moved in respect to health, differs from an object which can be heated. This latter is moved in respect to heating.

             640. Next where he says, 'And there are the same . . .' (224 a 31), he distinguishes motion per se from motion per accidens in respect to the mover.

             He says that the above distinction, which was made in respect to the mobile object, can likewise be applied to the mover.

             For a thing is said to move in three ways. First a thing moves per accidens, as when a musician builds. Secondly a thing moves in respect to a part insofar as a part moves, as when a man is said to hit because his hand hits. Thirdly a thing is said to move primarily and per se, as when a doctor cures.

             641. Next where he says, 'We have, then, the following . . .' (224 a 33), he proceeds to divide motion in the same way in respect to the terminus.

             First he sets forth some preambles. Secondly, where he says, 'Here also the same distinctions . . .' (224 b 16), he gives the division.

             Concerning the first part he makes three points. First he states how many things are required for motion. Secondly, where he says, '. . . that which is directly . . .' (224 b 2), he compares these things to each other. Thirdly, where he says, 'Now a definition of motion . . .' (224 b 10), he answers a certain difficulty.

             He says, therefore, first that five things are required for motion. The first requirement is a first mover from which the motion begins. Secondly, a mobile object which is moved is required. Thirdly there is the time in which the motion occurs. Besides these three things two termini are required: one from which the motion begins, and the other to which the motion proceeds. For all motion is from something to something.

             642. Next where he says, '. . . that which is directly . . .' (224 b 2), he compares these things to each other.

             First he compares the mobile object to the two termini of motion. Secondly, where he says, 'I do not include . . .' (224 b 6), he compares the two termini of motion to each other.

             He says, therefore, first that that which is moved primarily and per se is different from the terminus toward which the motion tends and from the terminus from which the motion began. This is clear in regard to wood, hot, and cold. For in the motion of heating the wood is a mobile object which differs from hot, which is the terminus to which, and from cold, which is the terminus from which.

             He says that that which is moved primarily is other than both termini because there is nothing to prevent that which is moved per accidens from being one of the termini. The object, i.e., the wood, becomes hot per se. But the privation and the contrary, i.e., cold, becomes hot per accidens, as was said in Book I.

             He next proves that the mobile object is other than both the termini from the fact that the motion is in the object, i.e., in the wood. However, the motion is in neither of the termini, neither in the species of white nor in the species of black. This is clear from the fact that that in which there is motion is moved. But the terminus of motion neither moves nor is moved, whether the terminus of motion be a quality, as in alteration, or a place, as in local motion, or a quantity, as in the motion of increase and decrease. Rather the mover moves the object which is moved toward the terminus to which. Hence, since the motion is in the object which is moved, but not in the terminus, it is clear that the mobile object is other than the terminus of the motion.

             643. Next where he says, 'I do not include . . .' (224 b 6), he compares the two termini to each other.

             He says that mutation is denominated by the terminus to which rather than by the terminus from which. Thus, corruption is called a mutation to non-being, although that which is corrupted is changed from being. Conversely, generation is a mutation to being, although it begins from non-being. The name of generation pertains to being; the name of corruption pertains to non-being. The reason [ratio] for this is that in mutation the terminus from which is removed and the terminus to which is acquired. Hence, motion seems to be repugnant to the terminus from which and to be in agreement with the terminus to which. And because of this motion is denominated by the terminus to which.

             644. Next where he says, 'Now a definition of motion . . .' (224 b 10), he answers a certain difficulty.

             Concerning this he makes three points.

             First he sets forth two points which are clear from the foregoing. The first of these is that it has been said in Book III what motion is. The second point is that he has just said above that the species, i.e., quality and place and any passive quality, which are the termini of motion, are not moved. For there is no motion in them, as was said. This is clear in knowledge, which is a certain species, and in heat, which is a certain passion or passive quality.

             Secondly, where he says, 'Here, however, a difficulty . . .' (224 b 13), he sets forth a third point concerning which there is a difficulty. He says that one might ask whether passions or passive qualities, like heat and coldness and whiteness and blackness, from which things are not moved, are motions.

             Thirdly, where he says, '. . . thus, there may be . . .' (224 b 14), he shows that, if this is held, then an inconsistency results. Since whiteness is a terminus toward which there is motion, then if whiteness is a motion, it follows that motion is the terminus of motion, which cannot be, as will be proven below. From this he determines the truth and says that whiteness is not a motion, rather whitening is. However, he adds 'perhaps', because he has not yet proven that motion is not terminated in motion.

             645. Next where he says, 'Here also the same distinctions . . .' (224 b 16), from the fact that the termini of motion are other than the mobile object and the mover, as was shown, he shows that, besides the division of motion taken in respect to the mover and the mobile object, motion is divided thirdly in respect to the terminus. And since the terminus to which names the motion rather than the terminus from which, as was said, he establishes this division of motion not in respect to the terminus from which but in respect to the terminus to which.

             He says that also in respect to the termini one can distinguish that which is moved per accidens, that which is moved in respect to a part and in respect to another, and that which is moved primarily and not in respect to another.

             The motion will be per accidens if that which becomes white is said to be changed to that which is understood or known by someone. For to be understood is accidental to the white thing.

             The motion will be in respect to a part if that which becomes white is said to be changed in colour. For it is said to be changed in colour because it is changed in whiteness, which is a part of colour. Another example is that I might say that one who comes to Athens comes to Europe, for Athens is a part of Europe.

             But the motion will be primary and per se if that which becomes white is said to be changed to a white colour.

             He does not divide motion in respect to time, which still remains. For time is related to motion as an extrinsic measure.

             646. Next where he says, 'It is now clear . . .' (224 b 22), he summarizes what he has said. He says that it is clear how something is moved per se, per accidens, and in respect to a part. Further it is clear how that which is primary and per se is found both in the mover and in the mobile object. For he has explained what a primary and per se mover is and what it is to be moved primarily and per se. Further he has shown that there is no motion in a species or quality which is the terminus of motion. Rather motion is in that which is moved, or in the mobile in respect to act, which is the same thing.

             647. Next where he says, 'Now accidental change . . .' (224 b 27), he shows what kind of motion must be treated.

             First he states his position. Secondly, where he says, 'An intermediate may be . . .' (224 b 30), he clarifies a certain thing which he has said.

             He says, therefore, first that mutation which is per accidens, taken in respect to either the mover or the mobile object or the terminus, must be omitted. The reason for this is that motion per accidens is indeterminate. For it is in all things as termini and in all time, and pertains to all objects and to all movers, since an infinity of things can be accidental to one thing. But mutation which is not per accidens is not in all things. Rather it is only in contraries and intermediaries in respect to motion in quantity, quality, and place, and in contradictories, in respect to generation and corruption whose termini are being and non-being. This is clear from induction. Only those things which are determinate fall under art, for there is no art of the infinite.

             648. Next where he says, 'An intermediate may be . . .' (224 b 30), he clarifies a certain thing which he has said; namely, there is motion in intermediaries.

             He says that motion occurs from an intermediary to either of the extremes, and vice versa, insofar as we can use the intermediary as a contrary in relation to either extreme. For the intermediary, insofar as it agrees with each extreme, is in a certain way each of them. Therefore, one can relate this to that and that to this. For example, one might say that an intermediary sound between the low and the high is low in relation to the high and high in relation to the low. Again, grey is white in relation to black, and vice versa.