19. Having established our four primary genera, it remains for us to enquire whether each of them of itself alone produces species. And especially, can Being be divided independently, that is without drawing upon the other genera? Surely not: the differentiae must come from outside the genus differentiated: they must be differentiae of Being proper, but cannot be identical with it.
Where then is it to find them? Obviously not in non-beings. If then in beings, and the three genera are all that is left, clearly it must find them in these, by conjunction and couplement with these, which will come into existence simultaneously with itself.
But if all come into existence simultaneously, what else is produced but that amalgam of all Existents which we have just considered [Intellect]? How can other things exist over and above this all-including amalgam? And if all the constituents of this amalgam are genera, how do they produce species? How does Motion produce species of Motion? Similarly with Stability and the other genera.
A word of warning must here be given against sinking the various genera in their species; and also against reducing the genus to a mere predicate, something merely seen in the species. The genus must exist at once in itself and in its species; it blends, but it must also be pure; in contributing along with other genera to form Substance, it must not destroy itself. There are problems here that demand investigation.
But since we identified the amalgam of the Existents [or primary genera] with the particular intellect, Intellect as such being found identical with Being or Substance, and therefore prior to all the Existents, which may be regarded as its species or members, we may infer that the intellect, considered as completely unfolded, is a subsequent.
Our treatment of this problem may serve to promote our investigation; we will take it as a kind of example, and with it embark upon our enquiry.