Further, the final cause is an end, and that sort of end which is not for the sake of something ebe, but for whose sake everything else is; so that if there is to be a last term of this sort, the process will not be infinite; but if there is no such term there will be no final cause. But those who maintain the infinite series destroy the Good without knowing it. Yet no one would try to do anything if he were not going to come to a limit. Nor would there be reason in the world; the reasonable man, at least, always acts for a purpose; and this is a limit, for the end is a limit.
But the formal cause, also, cannot be reduced always to another definition which is fuller in expression. For the original definition is always more of a definition, and not the later one; and in a series in which the first term is not correct, the next is not so either.—Further, those who speak thus destroy science; for it is not possible to have this till one comes to the indivisible concepts. And knowledge becomes impossible; for how can one think things that are infinite in this way? For this is not like the case of the line, to whose divisibility there is no stop, but which we cannot think if we do not make a stop; so that one who is tracing the infinitely divisible line cannot be counting the possibilities of section.
But further, the matter in a changeable thing must be cognized.
Again, nothing infinite can exist; and if it could, at least being infinite is not infinite.
But (2) if the kinds of causes had been infinite in number, then also knowledge would have been impossible; for we think
- i. e. one can reduce the definition of man as 'mortal rational animal' to 'mortal rational sensitive living substance', but one cannot carry on process ad infinitum.
- i. e. actually infinite.
- Sc. and therefore cannot form an infinite series.
- i. e. the notion of infinity does not contain an infinite number of marks.
effects not as water to air but as boy to man. It develops into them, and is not destroyed when they come into being.
(2) The clause beginning with ἐπεί seems, as is often the case, to be elliptical. The meaning probably is:—'Since the process of becoming is not infinite in the upward direction, <there must be an eternal first cause, but> a first cause by whose destruction something came to be could not be eternal.'