ct of faith is to be
perfect, there needs to be a habit in the will as well as in the
intellect: even as there needs to be the habit of prudence in the
reason, besides the habit of temperance in the concupiscible faculty,
in order that the act of that faculty be perfect. Now, to believe is
immediately an act of the intellect, because the object of that act
is "the true," which pertains properly to the intellect. Consequently
faith, which is the proper principle of that act, must needs reside
in the intellect.

Reply Obj. 1: Augustine takes faith for the act of faith, which is
described as depending on the believer's will, in so far as his
intellect assents to matters of faith at the command of the will.

Reply Obj. 2: Not only does the will need to be ready to obey but
also the intellect needs to be well disposed to follow the command of
the will, even as the concupiscible faculty needs to be well disposed
in order to follow the command of reason; hence there needs to be a
habit of virtue not only in the commanding will but also in the
assenting intellect.

Reply Obj. 3: Faith resides in the speculative intellect, as
evidenced by its object. But since this object, which is the First
Truth, is the end of all our desires and actions, as Augustine proves
(De Trin. i, 8), it follows that faith worketh by charity just as
"the speculative intellect becomes practical by extension" (De Anima
iii, 10).
_______________________

THIRD ARTICLE [II-II, Q. 4, Art. 3]

Whether Charity Is the Form of Faith?

Objection 1: It would seem that charity is not the form of faith.
For each thing derives its species from its form. When therefore two
things are opposite members of a division, one cannot be the form of
the other. Now faith and charity are stated to be opposite members of
a division, as different species of virtue (1 Cor. 13:13). Therefore
charity is not the form of faith.

Obj. 2: Further, a form and the thing of which it is the form are in
one subject, since together they form one simply. Now faith is in the
intellect, while charity is in the will. Therefore charity is not the
form of faith.

Obj. 3: Further, the form of a thing is a principle thereof. Now
obedience, rather than charity, seems to be the principle of
believing, on the part of the will, according to Rom. 1:5: "For
obedience to the faith in all nations." Therefore obedience rather
than charity, is the form of faith.

_On the contrary,_ Each thing work