Commentary Aristotle Physics
664. Consequently, it must be asserted that contrariety of differences in all the genera is based on the common root of contrariety, which is excellence and defect, to which set of contraries all others are reduced, as was explained in book 1. For all differences that divide a genus are so related that one is like abundance and the other is like defect in relation to the first. For which reason, Aristotle says in Metaphysics 8 that the definitions of things are like numbers in which the addition or subtraction of unity makes a different number. But nevertheless there does not need to be contrariety in every genus according to the proper account of this and that species, but only according to the common account of excellence and defect. For since contraries are things most distant, then, in order to have contrariety in a genus, there must be found two extremes that are most distant, such that between them fall all the things in that genus.
Yet that is not enough for positing motion in a genus, unless it is possible to pass without a break from one extreme to the other. Now, these two conditions are lacking in some genera, such as in numbers. For although all numbers differ according to excellence or defect, yet there cannot be found in that genus two extremes that are most distant; for it is possible to find a lowest number—that is, two—but not a greatest. In like manner, there are breaks between the species of number, since each number is formally constituted by unity, which is indivisible and not continuous with another unity.
The genus of substance is the same, since the forms of diverse species differ in respect to excellence and defect, inasmuch as one form is more noble than another, for which reason diverse qualities can be caused by diverse forms, as the objection mentions. Yet one form of a species is not contrary to another if you consider it in regard to its own specific account.
This is first of all because, when you are speaking of substantial forms, there is no maximum distance between any two forms such that you must pass through an orderly array of intermediate forms to go from the one extreme to the other.
Rather, when matter doffs one form, it can indiscriminately receive any other form without a specific order. For this reason, Aristotle says in De generatione et corruptione 2.4 that, when fire comes to be from earth, it is not necessary that the intermediate elements be involved at all.
A second reason is that, since the substantial essence of anything consists in an indivisible, no continuity can be found in substantial forms such as to make a continuous motion from one form to another by one form growing weak and the other growing strong.
Hence, the proof by which Aristotle shows that there is no motion in substance—because contrariety is absent—is a demonstration, and not merely a probability, as the Commentator seems to suggest. However, besides the reason given above, there is another that proves that, in substance, there is no motion: the subject of substantial form is merely a being in potency.
665. In qualities of the third species, the two above-mentioned characteristics of contraries (namely, continuity and maximum distance between the extremes) are clearly manifest:
first, because qualities can be weakened and strengthened so as to make for a continuous motion from quality to quality;
second, because there exists a maximum distance between two definite extremes of one genus, as black and white in the genus of color and sweet and bitter in the genus of taste.
However, in quantity and place, one of these two characteristics is evident, namely, continuity; but the other, which is maximum distance between definite extremes, is not found in them if you seize upon the general account of quantity and place. But it is found if you look for it in a definite thing. For example, in a definite species of animal or plant, there is a minimum quantity at which the motion of growing begins and a maximum at which it is terminated. Likewise, in place, there are involved two termini that are most distant in respect to some particular motion—from one of them motion begins and at the other it is terminated—and this happens whether the motion be natural or by force.
666. Then, at “nor is there motion in respect of relation” (225b11), he shows that there is no motion in the genus of relation. For in any genus in which per se motion exists, nothing can newly arise in that genus without its being changed, just as new color is never found in a colored object without that object’s being changed. But it does happen that something can be newly said truly of one thing relative to another, where the latter is changed but the former not. Therefore, in relation, motion is not found per se, but only per accidens, inasmuch as a new relation follows upon some change, such as when equality or inequality accompany a quantitative change or when resemblance or dissimilarity accompany qualitative change.
667. What has just been said seems to offer difficulty in respect of some types of relation and not of others. There are some relations that do posit no reality at all in the thing of which they are predicated. This happens sometimes on the side of both extremes, as when it is said that the same thing is the same thing to the same thing, for this relation of identity would be multiplied to infinity if each thing were the same as itself through an added relation, since it is evident that each thing is the same as itself. Consequently, this relation exists only in the reasoning power, inasmuch as the reason takes one and the same thing as the two extremes of the relation. The same thing is true in many other relations.
But there are some relations in which one relation is really in one of the extremes, but only according to reason in the other, such as knowledge and the knowable. For “knowable” is a relative term that is applied to an object not because it is related to something else by reason of a relationship existing in the object, but because that something else is related to it, as is clear in Metaphysics 5. Another example is when a pillar is said to be on the right of an animal, for right and left are real relations in the animal (because animals possess definite energies on which these relations are based), but in the pillar they are not present in reality, but only according to reason, for the pillar lacks the energies that are the basis of these relations.
Again, there are relationships in which both extremes possess a real relation, such as equality and resemblance, for both extremes possess the quantity or the quality that serves as the root of the relationship. The same is apparent in many other relationships.
Now, in those relations that put something real in only one of the extremes, it is not hard to see that, if the extreme in which the relation really exists undergoes a change, something new will be said correlatively of the other extreme, even though it remains unchanged, since nothing really happened to it. However, in those cases in which the relation is really found in both extremes, it is hard to see how something relative can be said of A if B changes but A does not, for nothing can be newly acquired by A without A being changed.
Hence, it must be said that, if some change in someone makes him equal to me (even though I do not change at all), that equality was in a sense in me in advance as in its root, from which that equality has real existence: since I have such and such a quantity, it belongs to me to be equal to anything having the same quantity. Hence, when someone newly acquires that quantity, that common basis of equality reaches to him, which is why nothing new happens to me, when I begin to be equal to someone, since he changes.
668. Then, at “nor is there motion in respect of agent and patient” (225b13), he proves that motion is not in the genera of action and passion. For action and passion do not differ really from motion, but they add to it something of reason, as we said in book 3. Hence, it is the same thing to say that motion is present in acting and being acted upon as to say that motion is present in motion.
Therefore, in regard to this, he does three things:
first, he proposes what he intends;
second, he proves his proposition, at “for in the first place” (225b16; [669]);
third, he posits a distinction that will explain the proposition, at “to sum up, then” (226a19; [677]).
Accordingly, he says (225b16) that, just as motion is not found in something relative, so also there is no motion of an agent or a patient and, strictly speaking, not even of the mover and moved, for there cannot be motion of motion or a coming to be of coming to be, which are types of change, nor even a change of change (which is the genus) or a ceasing to be of a ceasing to be.
669. Then, at “for in the first place” (225b16), he proves that there cannot be change of changes. And he does this with six arguments.
The first is that there are two ways of interpreting change of change. In one sense, it means that there is a change of a change, that is, of the subject that is being changed, as there is change of a man because the man is being changed from white to black (for example). In this interpretation, there would be a motion or change of a change or motion as of a subject in such a way that the motion or change is changed—for example, that the change gets hot or cold or changes place or grows or decreases. This, however, is impossible, because change is not listed among the subjects of change, for it is not a substance existing by itself. So there cannot be change of change in this sense.
670. In another way, it can be interpreted that there be change of change as of a terminus, such that a subject is moved from one type of change to another, such as from getting hot to getting cold or healthy, such that two changes are understood to be the termini of one change, as sickness and health are taken as the two termini of a change when a man is changed from health to sickness. But it is not possible for a subject to be moved per se from one change to another, but only per accidens.
And that it is impossible per se he proves in two ways.
The first is this. Every motion is a change from one definite form to another definite form; even generation and ceasing to be, which are codivided with motion, have their definite termini. But there is this difference: generation and corruption are to opposite termini of a particular kind, that is, according to contradiction, whereas motion tends to an opposite terminus of a different kind, that is, according to contrariety.