15. However, how do four of these genera complete being, without
nevertheless constituting the suchness (or, quality) of being? for they
do not form a "certain being." The primary Essence has already been
mentioned; and it has been shown that neither movement, difference, nor
identity are anything else. Movement, evidently, does not introduce any
quality in essence; nevertheless it will be wise to study the question
a little more definitely. If movement be the actualization of being, if
essence, and in general all that is in the front rank be essentially an
actualization, movement cannot be considered as an accident. As it is,
however, the actualization of the essence which is in actualization,
it can no longer be called a simple complement of "being," for it is
"being" itself. Neither must it be ranked amidst things posterior
to "being," nor amidst the qualities; it is contemporaneous with
"being," for you must not suppose that essence existed first, and then
moved itself (these being contemporaneous events). It is likewise
with stability; for one cannot say that essence existed first, and
then later became stable. Neither are identity or difference any
more posterior to essence; essence was not first unitary, and then
later manifold; but by its essence it is one manifold. So far as it
is manifold, it implies difference; while so far as it is a manifold
unity, it implies identity. These categories, therefore, suffice to
constitute "being." When one descends from the intelligible world
to inferior things, he meets other elements which indeed no longer
constitute absolute "being," but only a "certain being," that possesses
some particular quantity or quality; these are indeed genera, but
genera inferior to the primary genera.