MOVEMENTS DIVIDED IN NATURAL, ARTIFICIAL, AND VOLUNTARY.
26. Let us now examine the different kinds of movements. Shall we classify movements of displacement in movements upwards and downwards, rectilinear or curvilinear, or in movements of animate and inanimate beings? There is indeed a difference between the movement of inanimate beings, and that of animate beings; and these latter have different kinds of motion, such as walking, flying, and swimming. Their movements could also be analyzed in two other ways, according as it was conformable to, or against their nature; but this would not explain the outer differences of movements. Perhaps the movements themselves produce these differences, and do not exist without them; nevertheless, it is nature that seems to be the principle of the movements, and of their exterior differences. It would further be possible to classify movements as natural, artificial, and voluntary; of the natural, there are alteration and destruction; of the artificial, there are the building of houses, and construction of vessels; of the voluntary, there are meditation, learning, devoting oneself to political occupations, and, in general, speaking and acting. Last, we might, in growth, alteration and generation, distinguish the natural movement, and that contrary to nature; or even establish a classification founded on the nature of the subjects in which these movements occur.
DISTINCTION BETWEEN STABILITY AND STILLNESS.
27. Let us now study stability or stillness, which is the contrary of movement.[425] Are we to consider it itself a genus, or to reduce it to some one of the known genera? First, stability rather suits the intelligible world, and stillness the sense-world. Let us now examine stillness. If it be identical with stability, it is useless to look for it here below where nothing is stable, and where apparent stability is in reality only a slower movement. If stillness be different from stability, because the latter refers to what is completely immovable, and stillness to what is actually fixed, but is naturally movable even when it does not actually move, the following distinction should be established. If stillness here below be considered, this rest is a movement which has not yet ceased, but which is imminent; if by stillness is understood the complete cessation of movement in the moved, it will be necessary to examine whether there be anything here below that is absolutely without movement. As it is impossible for one thing to possess simultaneously all the species of movement, and as there are necessarily movements that are not realized in it—since it is usual to say that some particular movement is in something—when something undergoes no displacement, and seems still in respect to this movement, should one not say about it that in this respect it is not moving? Stillness is therefore the negation of movement. Now no negation constitutes a genus. The thing we are considering is at rest only in respect to local movement; stillness expresses therefore only the negation of this movement.
MOVEMENT IS MORE THAN THE NEGATION OF REST.
It may perhaps be asked, why is movement not rather the negation of rest? We shall then answer that movement (is something positive), that it brings something with it; that it has some efficiency, that it communicates an impulsion to the subject, that produces or destroys many things; stillness, on the contrary, is nothing outside of the subject which is still, and means no more than that the latter is still.
IN THE INTELLIGIBLE STABILITY DOES NOT IMPLY STILLNESS.
But why should we not regard the stability of intelligible things also as a negation of movement? Because stability is not the privation of movement; it does not begin to exist when movement ceases, and it does not hinder it from simultaneous existence with it. In intelligible being, stability does not imply the cessation of movement of that whose nature it is to move.[430] On the contrary, so far as intelligible being is contained in (or, expressed by) stability, it is stable; so far as it moves, it will ever move; it is therefore stable by stability, and movable by movement. The body, however, is no doubt moved by movement, but it rests only in the absence of movement, when it is deprived of the movement that it ought to have. Besides, what would stability be supposed to imply (if it were supposed to exist in sense-objects)? When somebody passes from sickness to health, he enters on convalescence. What kind of stillness shall we oppose to convalescence? Shall we oppose to it that condition from which that man had just issued? That state was sickness, and not stability. Shall we oppose to it the state in which that man has just entered? That state is health, which is not identical with stability. To say that sickness and health are each of them a sort of stability, is to consider sickness and health as species of stability, which is absurd. Further, if it were said that stability is an accident of health, it would result that before stability health would not be health. As to such arguments, let each reason according to his fancy!