entities would still permit intelligible nature ("being") to contain all the entities it contains as parts, while the aeon (or age, or eternity) might contain them as wholes, without any distinctions as parts; it contains them, in this respect, that they are called eternal on its account. FAULTS OF THE DEFINITION THAT ETERNITY IS AT REST, WHILE TIME IS IN MOTION. Some define eternity as the "rest"[440] of intelligible nature ("being"), just like time is defined as "motion" here below. In this case we should have to decide whether eternity be identical with rest in general, or only in such rest as would be characteristic of intelligible nature ("being"). If indeed eternity were to be identified with rest in general, we would first have to observe that rest could not be said to be eternal, any more than we can say that eternity is eternal, for we only call eternal that which participates in eternity; further, under this hypothesis, we should have to clear up how movement could ever be eternal; for if it were eternal, it would rest (or, it would stop). Besides, how could the idea of rest thus imply the idea of perpetuity, not indeed of that perpetuity which is in time, but of that of which we conceive when speaking of the aeonial (or, eternal)? Besides, if the rest characteristic of intelligible "being" in itself alone contain perpetuity, this alone would exclude from eternity the other genera (or categories) of existence. Further yet, eternity has to be conceived of as not only in rest, but (according to Plato[438]) also in unity, which is something that excludes every interval--otherwise, it would become confused with time;--now rest does not imply the idea of unity, nor that of an interval. Again, we assert that eternity resides in unity; and therefore participates in rest without being identified therewith. ETERNITY AS A UNION OF THE FIVE CATEGORIES.