Consequently, in speaking of (beings) other than (essence itself), as,
for instance, of man, we say simply "man" (without adding to it the
idea of unity[312]); if however we say "a man," it is to distinguish
him from two; if however we use the word one in still another sense, it
is by adding to it "some" (as, "someone"). Not so is it with essence;
we say, "being one," conceiving of "being" ("essence") and one, as if
forming a single whole, and in positing essence as one, we emphasize
its narrow affinity with the Good. Thus conceived, essence becomes
one;[313] and in the one finds its origin and goal. Nevertheless it is
not one as unity itself, but rather in a different manner, in this
sense that the (unity of essence) admits priority and posteriority.
What then is (the unity of essence)? Must it not then be considered
similar in all the parts (of essence), as something common to all (and
consequently, as forming a genus)? But in the first place, the point is
also something common to all the lines, and nevertheless it is not a
genus; in the numbers, unity is something common to all, and is not any
more of a genus. Indeed, the unity which is found in the monad, in the
dyad (or pair), and in other numbers, cannot be confused with unity in
itself. Then, nothing hinders there being in essence some anterior, and
other posterior parts, both simple and compound ones (which would be
impossible for the One in itself). Even if the unity found everywhere
in all the parts of essence were everywhere identical, by the mere fact
that it would offer no difference, it could not give rise to species,
and consequently, it could not be a genus.