Page - 706 - in The Complete Aristotle

circular motion, i.e. the eternity of the revolution of the heavens (a fact which approved itself on other and independent evidence),’ since precisely those movements which belong to, and depend upon, this eternal revolution ‘come- to-be’ of necessity, and of necessity ‘will be’. For since the revolving body is always setting something else in motion, the movement of the things it moves must also be circular. Thus, from the being of the ‘upper revolution’ it follows that the sun revolves in this determinate manner; and since the sun revolves thus, the seasons in consequence come-to-be in a cycle, i.e. return upon themselves; and since they come-to-be cyclically, so in their turn do the things whose coming-to-be the seasons initiate. Then why do some things manifestly come to-be in this cyclical fashion (as, e.g. showers and air, so that it must rain if there is to be a cloud and, conversely, there must be a cloud if it is to rain), while men and animals do not ‘return upon themselves’ so that the same individual comes-to-be a second time (for though your coming-to-be presupposes your father’s, his coming-to- be does not presuppose yours)? Why, on the contrary, does this coming-to-be seem to constitute a rectilinear sequence? In discussing this new problem, we must begin by inquiring whether all things ‘return upon themselves’ in a uniform manner; or whether, on the contrary, though in some sequences what recurs is numerically the same, in other sequences it is the same only in species. In consequence of this distinction, it is evident that those things, whose ‘substance’-that which is undergoing the process-is imperishable, will be numerically, as well as specifically, the same in their recurrence: for the character of the process is determined by the character of that which undergoes it. Those things, on the other hand, whose ‘substance’ is perish, able (not imperishable) must ‘return upon themselves’ in the sense that what recurs, though specifically the same, is not the same numerically. That why, when Water comes-to-be from Air and Air from Water, the Air is the same ‘specifically’, not ‘numerically’: and if these too recur numerically the same, at any rate this does not happen with things whose ‘substance’ comes-to-be-whose ‘substance’ is such that it is essentially capable of not-being. 706