Plotinos: Complete Works, v. 3 In Chronological Order,...

19. Since these four categories (which complete essence, namely, movement, stability, identity and difference) (with Essence as a fifth) constitute the primary genera, it remains to be examined whether each of them, by itself, can beget species; for instance, whether Essence, entirely by itself, could admit divisions in which the other categories would have no share whatever. No: for, in order to beget species, the genus would have to admit differences derived from outside; these differences would have to be properties belonging to Essence as such, without however being Essence. But from where then would Essence have derived them? Impossibly from what does not exist. If then they were necessarily derived from that which exists, as only three other genera of essences remain,324 evidently, Essence must have derived its differences from these genera, which associate themselves with Essence, while yet enjoying a simultaneous existence. But from this very fact that these genera enjoy an existence simultaneous (with Essence), they serve to constitute it, as it is composed of the gathering of these elements. How then could they be different from the whole that they constitute? How do these genera make species out of all (these beings)? How, for instance, could pure movement produce species of movement? The same question arises in connection with the other genera. Besides, we must avoid (two dangers:) losing each genus in its species, and, on the other hand, reducing it to the state of a simple predicate, by considering it only in its species.

The genus must exist both in its species and in itself. While blending (with the species), it must in itself remain pure and unblended; for, if it should contribute to "being" otherwise (by blending with its species), it would annihilate itself. Such are the questions that must be examined.