Enneads VI.2: The Categories of Plotinos
Unity Is Not Synonymous with Essence
It may be objected that the unity which is in essence, in movement, and the remainder of the genera, is common to all of them, and that one might therefore identify unity with essence. It must then be answered that, just as essence was not made a genus of other things because they were not what was essence, but that they were called essences in another sense, here likewise unity could not be a common attribute of other things, because there must be a primary Unity, and a unity taken in a secondary sense. If, on the other hand, it be said that unity should not be made a genus of all things, but something which exists in itself like the others, if afterwards unity be identified with essence, then, as essence has already been listed as one of the genera, we would be merely uselessly introducing a superfluous name. Distinguishing between unity and essence is an avowal that each has its separate nature; the addition of “something” to “one” makes a “certain one”; addition of nothing, on the other hand, allows unity to remain absolute, which cannot be predicated of anything. But why could this unity not be the First Unity, ignoring the absolute Unity? For we use “first Unity” as a designation of the essence which is beneath the “absolute Unity.” Because the Principle anterior to the first Essence (that is, the first and absolute Unity) is not essence; otherwise, the essence below Him would no longer be the first Essence; here, on the contrary, the unity which is above this unity is the absolute Unity. Besides, this unity which would be separated from essence only in thought, would not admit of any differences.
Besides, there are three alternatives. Either this unity alleged to inhere in essence will be, just like all other essences, a consequence of the existence of essence; and consequently, would be posterior to it. Or, it will be contemporaneous with essence and the other (categories); but a genus cannot be contemporaneous with the things of which it is the genus. The third possibility is that it may be anterior to essence; in which case its relation to Essence will be that of a principle, and no longer a genus containing it. If then unity be not a genus in respect to essence, neither can it be a genus in respect of other things; otherwise, we would have to say of essence also that it was a genus embracing everything else.
ESSENCE CANNOT BECOME A GENUS SO LONG AS IT REMAINS ONE.
Considering unity according to its essence, it seems to fuse and coincide with absolute Essence, for essence, so far as it trends towards unity, is a single essence; but in so far as it is posterior to unity, it becomes all things it can be, and becomes manifold. Now, so far as essence remains one and does not divide, it could not constitute a genus.
ELEMENTS OF ESSENCE CAN BE SAID TO BE ONE ONLY FIGURATIVELY.
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; 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).