enus, and constitute the
species of that genus, must, as the Philosopher says (Metaph. vii,
12), divide that genus essentially: and if they divide it
accidentally, the division is incorrect: as, if one were to say:
"Animals are divided into rational and irrational; and the irrational
into animals with wings, and animals without wings"; for "winged" and
"wingless" are not essential determinations of the irrational being.
But the following division would be correct: "Some animals have feet,
some have no feet: and of those that have feet, some have two feet,
some four, some many": because the latter division is an essential
determination of the former. Accordingly when the object is not of
itself ordained to the end, the specific difference derived from the
object is not an essential determination of the species derived from
the end, nor is the reverse the case. Wherefore one of these species
is not under the other; but then the moral action is contained under
two species that are disparate, as it were. Consequently we say that
he that commits theft for the sake of adultery, is guilty of a
twofold malice in one action. On the other hand, if the object be of
itself ordained to the end, one of these differences is an essential
determination of the other. Wherefore one of these species will be
contained under the other.

It remains to be considered which of the two is contained under the
other. In order to make this clear, we must first of all observe that
the more particular the form is from which a difference is taken, the
more specific is the difference. Secondly, that the more universal an
agent is, the more universal a form does it cause. Thirdly, that the
more remote an end is, the more universal the agent to which it
corresponds; thus victory, which is the last end of the army, is the
end intended by the commander in chief; while the right ordering of
this or that regiment is the end intended by one of the lower
officers. From all this it follows that the specific difference
derived from the end, is more general; and that the difference
derived from an object which of itself is ordained to that end, is a
specific difference in relation to the former. For the will, the
proper object of which is the end, is the universal mover in respect
of all the powers of the soul, the proper objects of which are the
objects of their particular acts.

Reply Obj. 1: One and the same thing, considered in its substance,
cannot be in t