cy is to overcome and rise above
obstacles. Now these two are not to be reduced to one principle: for
sometimes the soul busies itself with unpleasant things, against the
inclination of the concupiscible appetite, in order that, following
the impulse of the irascible appetite, it may fight against obstacles.
Wherefore also the passions of the irascible appetite counteract the
passions of the concupiscible appetite: since the concupiscence, on
being aroused, diminishes anger; and anger being roused, diminishes
concupiscence in many cases. This is clear also from the fact that
the irascible is, as it were, the champion and defender of the
concupiscible when it rises up against what hinders the acquisition of
the suitable things which the concupiscible desires, or against what
inflicts harm, from which the concupiscible flies. And for this reason
all the passions of the irascible appetite rise from the passions of
the concupiscible appetite and terminate in them; for instance, anger
rises from sadness, and having wrought vengeance, terminates in joy.
For this reason also the quarrels of animals are about things
concupiscible--namely, food and sex, as the Philosopher says [*De
Animal. Histor. viii.].

Reply Obj. 1: The concupiscible power regards both what is suitable
and what is unsuitable. But the object of the irascible power is to
resist the onslaught of the unsuitable.

Reply Obj. 2: As in the apprehensive powers of the sensitive part
there is an estimative power, which perceives those things which do
not impress the senses, as we have said above (Q. 78, A. 2); so also
in the sensitive appetite there is a certain appetitive power which
regards something as suitable, not because it pleases the senses, but
because it is useful to the animal for self-defense: and this is the
irascible power.

Reply Obj. 3: Hatred belongs simply to the concupiscible appetite:
but by reason of the strife which arises from hatred, it may belong
to the irascible appetite.
_______________________

THIRD ARTICLE [I, Q. 81, Art. 3]

Whether the irascible and concupiscible appetites obey reason?

Objection 1: It would seem that the irascible and concupiscible
appetites do not obey reason. For irascible and concupiscible are
parts of sensuality. But sensuality does not obey reason, wherefore
it is signified by the serpent, as Augustine says (De Trin. xii,
12,13). Therefore the irascible and concupiscible appetites do not
obey reason.

O