swering his
objections--if he has any--against faith. Since faith rests upon
infallible truth, and since the contrary of a truth can never be
demonstrated, it is clear that the arguments brought against faith
cannot be demonstrations, but are difficulties that can be answered.

Reply Obj. 1: Although arguments from human reason cannot
avail to prove what must be received on faith, nevertheless, this
doctrine argues from articles of faith to other truths.

Reply Obj. 2: This doctrine is especially based upon arguments
from authority, inasmuch as its principles are obtained by revelation:
thus we ought to believe on the authority of those to whom the
revelation has been made. Nor does this take away from the dignity of
this doctrine, for although the argument from authority based on human
reason is the weakest, yet the argument from authority based on divine
revelation is the strongest. But sacred doctrine makes use even of
human reason, not, indeed, to prove faith (for thereby the merit of
faith would come to an end), but to make clear other things that are
put forward in this doctrine. Since therefore grace does not destroy
nature but perfects it, natural reason should minister to faith as the
natural bent of the will ministers to charity. Hence the Apostle says:
"Bringing into captivity every understanding unto the obedience of
Christ" (2 Cor. 10:5). Hence sacred doctrine makes use also of the
authority of philosophers in those questions in which they were able
to know the truth by natural reason, as Paul quotes a saying of
Aratus: "As some also of your own poets said: For we are also His
offspring" (Acts 17:28). Nevertheless, sacred doctrine makes use of
these authorities as extrinsic and probable arguments; but properly
uses the authority of the canonical Scriptures as an incontrovertible
proof, and the authority of the doctors of the Church as one that may
properly be used, yet merely as probable. For our faith rests upon the
revelation made to the apostles and prophets who wrote the canonical
books, and not on the revelations (if any such there are) made to
other doctors. Hence Augustine says (Epis. ad Hieron. xix, 1): "Only
those books of Scripture which are called canonical have I learned to
hold in such honor as to believe their authors have not erred in any
way in writing them. But other authors I so read as not to deem
everything in their works to be true, merely on account of their
having so thought and wri