I read the Angelic Doctor daily, and yesterday I read this:
“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.” Summa, Pt. 1, Q. 1, Art. 8 (I answer)
Retrieved January 12, 2014 from http://www.newadvent.org/summa/1001.htm#article8
Reading Aquinas is walking on one of the seminal paths of Catholicism, virtually scripture, overshadowed only by the Gospel itself.