od, drink, and the like: and concupiscence of such pleasurable
things is said to be natural. Secondly, a thing is pleasurable
because it is apprehended as suitable to the animal: as when one
apprehends something as good and suitable, and consequently takes
pleasure in it: and concupiscence of such pleasurable things is said
to be not natural, and is more wont to be called "cupidity."

Accordingly concupiscences of the first kind, or natural
concupiscences, are common to men and other animals: because to both
is there something suitable and pleasurable according to nature: and
in these all men agree; wherefore the Philosopher (Ethic. iii, 11)
calls them "common" and "necessary." But concupiscences of the second
kind are proper to men, to whom it is proper to devise something as
good and suitable, beyond that which nature requires. Hence the
Philosopher says (Rhet. i, 11) that the former concupiscences are
"irrational," but the latter, "rational." And because different men
reason differently, therefore the latter are also called (Ethic. iii,
11) "peculiar and acquired," i.e. in addition to those that are
natural.

Reply Obj. 1: The same thing that is the object of the natural
appetite, may be the object of the animal appetite, once it is
apprehended. And in this way there may be an animal concupiscence of
food, drink, and the like, which are objects of the natural appetite.

Reply Obj. 2: The difference between those concupiscences that are
natural and those that are not, is not merely a material difference;
it is also, in a way, formal, in so far as it arises from a
difference in the active object. Now the object of the appetite is
the apprehended good. Hence diversity of the active object follows
from diversity of apprehension: according as a thing is apprehended
as suitable, either by absolute apprehension, whence arise natural
concupiscences, which the Philosopher calls "irrational" (Rhet. i,
11); or by apprehension together with deliberation, whence arise
those concupiscences that are not natural, and which for this very
reason the Philosopher calls "rational" (Rhet. i, 11).

Reply Obj. 3: Man has not only universal reason, pertaining to the
intellectual faculty; but also particular reason pertaining to the
sensitive faculty, as stated in the First Part (Q. 78, A. 4; Q. 81,
A. 3): so that even rational concupiscence may pertain to the
sensitive appetite. Moreover the sensitive appetite can be moved by
the univer