We proceed to the fourth article thus:
1. It seems that the object of faith is something which is seen. For our Lord said to Thomas: "Thomas, because thou hast seen me, thou hast believed." Thus the same thing is both seen and believed.
2. Again, the apostle says in I Cor.13:12: "For now we see through a glass, darkly" -- and he is speaking of the knowledge of faith. Hence what is believed is seen.
3. Again, faith is a kind of spiritual light. Now by light of any kind, something is seen. Hence faith is of things that are seen.
4. Again, as Augustine says (De Verb. Dom., Sermo.33, cap.5): "Every sense is called sight." Now faith is of things that are heard, according to Rom.10:17: "faith cometh by hearing." Hence faith is of things that are seen.
On the other hand: the apostle says: "Faith is . . . the evidence of things not seen" (Heb.11:1).
I answer: faith implies intellectual assent to that which is believed. But there are two ways in which the intellect gives its assent. In the first way, it is moved to give its assent by the object itself, which is either known in itself, as first principles are obviously known, since the intellect understands them, or known through something else that is known, as are conclusions which are known scientifically. In the second way, the intellect gives its assent not because it is convinced by the object itself, but by voluntarily preferring the one alternative to the other. If it chooses with hesitation, and with misgivings about the other alternative, there will be opinion. If it chooses with assurance, and without any such misgivings, there will be faith. Now those things are said to be seen which of themselves move our intellect or sense to know them. Hence it is clear that neither faith nor opinion can be of things that are seen, whether by sense or by the intellect.
On the first point: Thomas "saw one thing and believed another." When he said: "my Lord and my God," he saw a man. But by faith he confessed God.
On the second point: things which are held in faith may be considered under two aspects. If we consider them in their particularity, they cannot be both seen and believed at the same time, as we have said above. But if we consider them in their general aspect as things which can be believed, they are seen by him who believes them. For a man would not believe them if he did not see that they were to be believed, either on the evidence of signs, or on some other similar evidence.
On the third point: the light of faith enables us to see what we believe.  Just as the habit of any other virtue enables a man to see what is becoming for him in respect of it, so does the habit of faith incline a man's mind to assent to such things as are becoming for true faith, but not to other things.
On the fourth point: it is the words signifying the things of faith that are heard, not the things of faith themselves. Hence it does not follow that these things are seen.
 Cod. Alcan. et Camer.: "to see that the things believed are." In margin Alcan.: "to see that the things believed are true."