As stated above (Q. 58, AA. 1, 2, 3), the moral
virtues are habits of the appetitive faculty. Now habits differ
specifically according to the specific differences of their objects,
as stated above (Q. 54, A. 2). Again, the species of the object of
appetite, as of any thing, depends on its specific form which it
receives from the agent. But we must observe that the matter of the
passive subject bears a twofold relation to the agent. For sometimes
it receives the form of the agent, in the same kind specifically as
the agent has that form, as happens with all univocal agents, so that
if the agent be one specifically, the matter must of necessity
receive a form specifically one: thus the univocal effect of fire is
of necessity something in the species of fire. Sometimes, however,
the matter receives the form from the agent, but not in the same kind
specifically as the agent, as is the case with non-univocal causes of
generation: thus an animal is generated by the sun. In this case the
forms received into matter are not of one species, but vary according
to the adaptability of the matter to receive the influx of the agent:
for instance, we see that owing to the one action of the sun, animals
of various species are produced by putrefaction according to the
various adaptability of matter.

Now it is evident that in moral matters the reason holds the place of
commander and mover, while the appetitive power is commanded and
moved. But the appetite does not receive the direction of reason
univocally so to say; because it is rational, not essentially, but by
participation (Ethic. i, 13). Consequently objects made appetible by
the direction of reason belong to various species, according to their
various relations to reason: so that it follows that moral virtues
are of various species and are not one only.

Reply Obj. 1: The object of the reason is truth. Now in all moral
matters, which are contingent matters of action, there is but one
kind of truth. Consequently, there is but one virtue to direct all
such matters, viz. prudence. On the other hand, the object of the
appetitive power is the appetible good, which varies in kind
according to its various relations to reason, the directing power.

Reply Obj. 2: This formal element is one generically, on account of
the unity of the agent: but it varies in species, on account of the
various relations of the receiving matter, as explained above.

Reply Obj. 3: Moral matters do not rec