10. In what sense, therefore, could each of the elements of essence be called "one"? In that it is something unitary, without being unity itself; for what is a "certain one" is already manifold. No species is "one" except figuratively[306]; for in itself it is manifold. It is in the same sense that, in this sense-world, we say that an army, or a choric ballet, constitute a unity. Not in such things is absolute unity; and therefore it may not be said that unity is something common. Neither does unity reside in essence itself, nor in the individual essences; therefore, it is not a genus. When a genus is predicated of something, it is impossible to predicate of the same thing contrary properties; but of each of the elements of universal essence it is possible to assert both unity and its opposite. Consequently (if we have called unity a genus), after having predicated of some essence unity as a genus, we would have affirmed, of the same essence, that unity was not a genus. Unity, therefore, could not be considered one of the primary genera; for essence is no more one than it is manifold. As to the other genera, none of them is one without being manifold; much less could unity be predicated of the secondary genera of which each is quite manifold. Besides, no genus, considered in its totality, is unitary; so that if unity were a genus, it would merely thereby cease being unity; for unity is not a number, and nevertheless it would become a number in becoming a genus. Of course, numbers include an alleged unity, as soon as we try to erect it into a genus, it is no longer a unity, in a strict sense. Among numbers unity is not applied to them as would have been a genus; of such unity it is merely said that it is among numbers, not that it is a genus; likewise, if unity were among the essences, it would not be there as genus of essence, nor of anything else, nor of all things. Again, just as the simple is the principle of the composite without being considered a genus in respect to it--then it would be simultaneously simple and composite--so, if one were considered to be a principle, it could not be a genus in respect to things subsumed under it; and therefore will be a genus neither for essence, nor for other (categories or things). VARIOUS ARGUMENTS AGAINST UNITY AS A CATEGORY. If unity were to be considered a genus, it could be that only in respect to the things of which each is said to be one;[309] as if, for instance, one should, from "being," deduce the unity contained within it. Unity would then be the genus of certain things; for just as essence is a genus, not in respect to all things, but in respect to those species that possess essence, so unity would be a genus in respect to the species that possess unity. This, however, is impossible; for things do not differ in respect to unity, as they do in respect to essence.