This, however, does not proceed to infinity; but it stops somewhere, and there will be something which will be primarily the cause of motion: for if it be not so, but there is a progression to infinity; let A be moved by B, B by C, and C by D; and, after this manner, let there be a progression to infinity. Since therefore the mover is at the same time itself moved, it is evident that A and B will be at the same time moved: for B being moved, A also will be moved; and hence B being moved, C also will be moved; and C being moved, D will be moved. rrhe motion, therefore, of A, B, and C, and of each of the rest, will take place at the same time. Hence we shall be able to assume each of these: for though each is moved by each, nevertheless there is a motion of each which is one in number, and not infinite with respect to boundaries; since whatever is moved, is moved from something into something: for it happens that there is either the same motion in number, or in genus, or in species. I call, therefore, that motion the same in number, which proceeds from the same into the same in number, and in a time which is the same in number; as, for instance, from this white which is one in number, into this black, according to this time which is one in number: for if according to another time, there will no longer be one motion in number, but in species. But the motion is the same in genus, which is produced in the same category of substance, or of some other genus; and the motion is the same in species, which proceeds from the same thing in species to the same thing in species; as, from white into black, or from good into evil. These things, however, have been spoken of before. Let the motion therefore of A be assumed, and let it be E; the motion of B, and let it be F; and the motion of C D, and let it be G H. Let the time also in which A is moved be K. Since therefore the motion of A is definite, the time also will be definite, and not infinite. But in the same time A and B were moved, and each of the rest. It happens, therefore, that the motion E F G H being infinite, will be accomplished in a finite time K: for in the time in which A was moved, all the rest in succession after A, and which are infinite, were moved; so that they will be moved in the same time: for either the motion of A will be equal to the motion of B, and to the motion of the rest, or it will be greater. It is, however, of no consequence, since it will entirely happen that an infinite motion will be effected in a finite time; which is impossible. Thus, therefore, that which was investigated from the beginning, may appear to be demonstrated: it is not however because no absurdity happens; for it is possible that there may be an infinite motion in a finite time, yet not the same, but another and another, many and infinite things being moved; which also happens in the particulars now under consideration. But if it is necessary that that which is first moved according to place, and with a corporeal motion, should touch or be continued with the mover, as we see this happens to be the case in all things; from all, the whole will be one, or continued. Let this, therefore, which may take place, be assumed, and let the magnitude, or that which is continued, be A B C D; and let the motion of this be E F G H. But it is of no consequence, whether it be finite or infinite; for in a finite time K, either that which is infinite, or that which is finite, will be similarly moved ; and either of these is impossible. It is evident, therefore, that at some time or other it will stand still, and that the being moved by another will not always proceed to infinity, but that tbere will be something which will be first moved. But it ought not to be any objection that this has been demonstrated from something being supposed; for that which is possible being supposed, it is requisite that no absurdity should happen.
