tly ruled, is entirely due
to the rational powers. Now "virtue is that by which we live
rightly," as we have said above (Q. 55, A. 4). Therefore virtue is
not in the irascible and concupiscible powers, but only in the
rational powers.

Obj. 4: Further, "the principal act of moral virtue is choice"
(Ethic. viii, 13). Now choice is not an act of the irascible and
concupiscible powers, but of the rational power, as we have said
above (Q. 13, A. 2). Therefore moral virtue is not in the irascible
and concupiscible powers, but in the reason.

_On the contrary,_ Fortitude is assigned to the irascible power, and
temperance to the concupiscible power. Whence the Philosopher (Ethic.
iii, 10) says that "these virtues belong to the irrational part of
the soul."

_I answer that,_ The irascible and concupiscible powers can be
considered in two ways. First, in themselves, in so far as they are
parts of the sensitive appetite: and in this way they are not
competent to be the subject of virtue. Secondly, they can be
considered as participating in the reason, from the fact that they
have a natural aptitude to obey reason. And thus the irascible or
concupiscible power can be the subject of human virtue: for, in so
far as it participates in the reason, it is the principle of a human
act. And to these powers we must needs assign virtues.

For it is clear that there are some virtues in the irascible and
concupiscible powers. Because an act, which proceeds from one power
according as it is moved by another power, cannot be perfect, unless
both powers be well disposed to the act: for instance, the act of a
craftsman cannot be successful unless both the craftsman and his
instrument be well disposed to act. Therefore in the matter of the
operations of the irascible and concupiscible powers, according as
they are moved by reason, there must needs be some habit perfecting
in respect of acting well, not only the reason, but also the
irascible and concupiscible powers. And since the good disposition of
the power which moves through being moved, depends on its conformity
with the power that moves it: therefore the virtue which is in the
irascible and concupiscible powers is nothing else but a certain
habitual conformity of these powers to reason.

Reply Obj. 1: The irascible and concupiscible powers considered in
themselves, as parts of the sensitive appetite, are common to us and
dumb animals. But in so far as they are rational by participati