Reply Obj. 2: Those things which come under faith can be considered in two ways. First, in particular; and thus they cannot be seen and believed at the same time, as shown above. Secondly, in general, that is, under the common aspect of credibility; and in this way they are seen by the believer. For he would not believe unless, on the evidence of signs, or of something similar, he saw that they ought to be believed.
Reply Obj. 3: The light of faith makes us see what we believe. For just as, by the habits of the other virtues, man sees what is becoming to him in respect of that habit, so, by the habit of faith, the human mind is directed to assent to such things as are becoming to a right faith, and not to assent to others.
Reply Obj. 4: Hearing is of words signifying what is of faith, but not of the things themselves that are believed; hence it does not follow that these things are seen. _______________________
FIFTH ARTICLE [II-II, Q. 1, Art. 5]
Whether Those Things That Are of Faith Can Be an Object of Science [*Science is certain knowledge of a demonstrated conclusion through its demonstration]?
Objection 1: It would seem that those things that are of faith can be an object of science. For where science is lacking there is ignorance, since ignorance is the opposite of science. Now we are not in ignorance of those things we have to believe, since ignorance of such things savors of unbelief, according to 1 Tim. 1:13: "I did it ignorantly in unbelief." Therefore things that are of faith can be an object of science.
Obj. 2: Further, science is acquired by reasons. Now sacred writers employ reasons to inculcate things that are of faith. Therefore such things can be an object of science.
Obj. 3: Further, things which are demonstrated are an object of science, since a "demonstration is a syllogism that produces science." Now certain matters of faith have been demonstrated by the philosophers, such as the Existence and Unity of God, and so forth. Therefore things that are of faith can be an object of science.
Obj. 4: Further, opinion is further from science than faith is, since faith is said to stand between opinion and science. Now opinion and science can, in a way, be about the same object, as stated in Poster. i. Therefore faith and science can be about the same object also.
On the contrary, Gregory says (Hom. xxvi in Evang.) that "when a thing is manifest, it is the object, not of faith, but of perception." Therefore things that are of faith are not the object of perception, whereas what is an object of science is the object of perception. Therefore there can be no faith about things which are an object of science.