REASONS WHY MOVEMENT IS A CATEGORY.
21. Let us pass to movement.[415] Admittedly movement is a genus with the following characteristics: first, movement cannot be reduced to any other genus; then, nothing higher in the scale of being can be predicated of it; last, it reveals a great number of differences which constitute species.
MOVEMENT CANNOT BE REDUCED TO ANY HIGHER GENUS.
To what genus could (movement) be reduced? It constitutes neither the being nor the quality of the (being) in which it exists. It is not even reducible to action, for in passion (or, experience) there are several kinds of movements; and it is the actions and passions which are reducible to movement. Further, movement need not necessarily be a relative merely because movement does not exist in itself, that it belongs to some being, and that it exists in a subject; otherwise, we should have to classify quality also as a relation; for quality belongs to some (being) and exists in a subject; it is not so however, with a quantity. It might be objected that, though each of them exist in some subject, the one by virtue of its being a quality, and the other, of being a quantity, they themselves are not any the less species of essences. The same argument would apply to movement; though it belong to some subject, it is something before belonging to a subject, and we must consider what it is in itself. Now what is relative is not at first something by itself, and then the predicate of something else;[416] but what is born of the relation existing between two objects, is nothing else outside the relation to which it owes its name; thus the double, so far as it is called doubleness, is neither begotten, nor exists except in the comparison established between it and a half, since, not being conceived of before, it owes its name and its existence to the comparison thus established.
IS CHANGE ANTERIOR TO MOVEMENT?
What then is movement? While belonging to a subject, it is something by itself before belonging to a subject, as are quality, quantity, and being. To begin with, nothing is predicated before it, and of it, as a genus. Is change[417] anterior to movement? Here change is identical with movement, or if change is to be considered a genus, it will form a genus to be added to those already recognized. Besides, it is evident that, on this hypothesis, movement will become a species, and to it will be opposed, as another species, "generation," as, for instance, "generation" is a change, but not a movement.[418] Why then should generation not be a movement? Is it because what is generated does not yet exist, and because movement could not exist in non-being? Consequently, neither will generation be a change. Or is this so because generation is an alteration and increase, and because it presupposes that certain things are altered, and increase? To speak thus is to busy ourselves with things that precede generation. Generation presupposes production of some other form; for generation does not consist in an alteration passively undergone, such as being warmed, or being whitened; such effects could be produced before realization of the generation. What then occurs in generation? There is alteration. Generation consists in the production of an animal or plant, in the reception of a form. Change is much more reasonably to be considered a species, than movement; because the word change means that one thing takes the place of another, while movement signifies the actualization by which a being passes from what is proper to it, to what is not, as in the translation from one place to another. If that be not admitted (to define movement), it will at least have to be acknowledged that the action of studying it, as that of playing the lyre, and in general, all the movements that modify a habit, would be subsumed within our definition. Alteration therefore could not be anything else but a species of movement; since it is a movement which produces passage from one state to another.[419]
DEFINITION OF ALTERATION.
22. Granting that alteration is the same thing as movement, so far as the result of movement is to render something other than it was, (we still have to ask) what then is movement? To indulge in a figurative expression,[343] it is the passage of potentiality to the actualization of which it is the potentiality.[420]
MOVEMENT AS A FORM OF POWER.
Let us, indeed, suppose, that something which formerly was a potentiality succeeds in assuming a form, as "potentiality that becomes a statue," or that passes to actualization, as a man's walk.[421] In the case where the metal becomes a statue, this passage is a movement; in the case of the walking, the walk itself is a movement, like the dance, with one who is capable of it. In the movement of the first kind, where the metal passes into the condition of being a statue, there is the production of another form which is realized by the movement.[422] The movement of the second kind, the dance, is a simple form of the potentiality, and, when it has ceased, leaves nothing that subsists after it.[423]