Thus, in addition to the other three [Being, Motion, Stability], we are obliged to posit the further two, Identity and Difference, so that we have in all five genera. In so doing, we shall not withhold Identity and Difference from the subsequents of the Intellectual order; the thing of Sense has, it is clear, a particular identity and a particular difference, but Identity and Difference have the generic status independently of the particular.
They will, moreover, be primary genera, because nothing can be predicated of them as denoting their essential nature. Nothing, of course we mean, but Being; but this Being is not their genus, since they cannot be identified with any particular being as such. Similarly, Being will not stand as genus to Motion or Stability, for these also are not its species. Beings [or Existents] comprise not merely what are to be regarded as species of the genus Being, but also participants in Being. On the other hand, Being does not participate in the other four principles as its genera: they are not prior to Being; they do not even attain to its level.