If those blessed ancient philosophers had not already uttered their views about time, we would only need to add to the idea of eternity what we have to say of the idea of time, and to set forth our opinion on the subject, trying to make it correspond with the already expressed notion of eternity. But we now must examine the most reasonable opinions that have been advanced about time, and observe how far our own opinion may conform thereto. TIME CONSIDERED EITHER AS MOTION; AS SOMETHING MOVABLE; OR SOMETHING OF MOTION. To begin with, we may divide the generally accepted opinions about time into three classes: time as movement, as something movable, or as some part of movement. It would be too contrary to the notion of time to try to define it as rest, as being at rest, or as some part of rest; for time is incompatible with identity (and consequently with rest, and with what is at rest). Those who consider time as movement, claim that it is either any kind of movement, or the movement of the universe. Those who consider it as something movable are thinking of the sphere of the universe; while those who consider time as some part of movement consider it either as the interval of movement, or as its measure, or as some consequence of movement in general, or regular movement. POLEMIC AGAINST THE STOICS; TIME IS NOT MOVEMENT. 7. (8). Time cannot (as the Stoics claim,[447]) be movement. Neither can we gather together all movements, so as to form but a single one, nor can we consider the regular movement only; for these two kinds of motion are within time. If we were to suppose that there was a movement that did not operate within time, such a movement would still be far removed from being time, since, under this hypothesis, the movement itself is entirely different from that in which the movement occurs. Amidst the many reasons which, in past and present, have been advanced to refute this opinion, a single one suffices: namely, that movement can cease and stop, while time never suspends its flight. To the objection that the movement of the universe never stops, we may answer that this movement, if it consist in the circular movement (of the stars, according to Hestius of Perinthus; or of the sun, according to Eratosthenes[447]) operates within a definite time, at the end of which it returns to the same point of the heavens, but it does not accomplish this within the same space of time taken up in fulfilling the half of its course. One of these movements is only half of the other, and the second is double. Besides, both, the one that runs through half of space, and the one that runs through the whole of it, are movements of the universe. Besides, it has been noticed that the movement of the exterior sphere is the swiftest. This distinction supports our view, for it implies that the movement of this sphere, and the time used to operate it, are different entities; the most rapid movement is the one