We proceed to the first article thus:

It seems that the apostle's definition of faith (Heb.11:1) is not satisfactory -- "Faith is the substance of things hoped for, the evidence of things not seen." For no quality is a substance, and it was said in 12ae, Q.72, Art.3, that faith is a quality, since it is a theological virtue. It follows that faith is not a substance.

2. Again, different objects belong to different virtues. Now a thing hoped for is the object of hope. Hence it should not be included in the definition as if it were the object of faith.

3. Again, faith is made perfect by charity, rather than by hope. For charity is the form of faith, as will be shown in Art.3. "Things loved" should therefore be included in the definition, rather than "things hoped for."

4. Again, the same thing should not be included in different genera. Now "substance" and "evidence" are different genera, and neither is intended as a subalternative. It is therefore wrong to define faith as both "substance" and "evidence." Hence faith is improperly described.

5. Again, evidence makes apparent the truth of that in evidence of which it is brought. Now when the truth about a thing is apparent, the thing is said to be seen. It is therefore contradictory to speak of "the evidence of things not seen," since evidence causes something to be seen which was previously unseen. It is therefore wrongly said "of things not seen." Hence faith is improperly described.

On the other hand: the authority of the apostle is sufficient.

I answer: there are some who say that these words of the apostle are not a definition of faith, on the ground that definition exhibits the "what," or essence of a thing, as is maintained in 6 Metaph., text 19. But if anyone consider the matter aright, he will see that this description indicates everything by means of which faith could be defined, even though it is not expressed in the form of a definition. Philosophers indicate the principles of syllogism in a similar way, without making use of the syllogistic form.

To make this clear, we may observe that faith is bound to be defined in terms of its own proper act in relation to its own proper object. For faith is a habit, and habits are known through their acts, which are known through their objects. Now as we said in Q.2, Arts.2 and 3, the act of faith is to believe, and belief is an act of the intellect as directed to one object by the will. The act of faith is therefore related both to the object of the will, which is the good and the end, and to the object of the intellect, which is the truth. Further, since faith is a theological virtue, as we said in 12ae, Q.92, Art.3, it has the same thing for its object as it has for its end. Consequently, the object of faith is bound to correspond, relatively, [56] to the end of faith. Now we have already said that the object of faith is the unseen first truth, together with what is consequential to the first truth (Q.1, Arts.1 and 4). It must therefore be as something unseen that the first truth relates to the act of faith as its end. Such is the nature of things hoped for. As the apostle says: "we hope for that we see not" (Rom.8:25). To see the truth is to possess it, whereas no one hopes for what he already possesses, since we hope for what we do not possess, as we observed in 12ae, Q.67, Art.4. The way in which the act of faith is related to the end of faith as the object of the will is accordingly indicated by the words: "faith is the substance of things hoped for." We often apply the name "substance" to the origin from which something is derived, especially when all that derives therefrom is virtually contained therein, as in a first principle. For example, we might say that its primary indemonstrable principles are the substance of a science, since they are the first things that we understand about the science, and since the whole science is virtually contained in them. It is in this sense that faith is said to be "the substance of things hoped for." For the first beginning of things hoped for arises in us as a result of the assent of faith, which virtually contains everything that is hoped for. We hope for the blessedness in which we shall see, face to face, the truth to which we now unite ourselves by the way of faith, as we said when speaking of blessedness in 12ae, Q.3, Art.8; Q.4, Art.3.

The way in which the act of faith relates to the object of faith as the object of the intellect, on the other hand, is indicated by the words "the evidence of things not seen," "evidence" standing for the result of evidence. The firm adherence of the intellect to the unseen truth of faith is here called "evidence" because evidence leads the intellect to accept something in a final manner. Thus another version reads "conviction," as in Augustine's Tract.79 in Joan., since the intellect is convinced by divine authority when it assents to what it does not see. Hence if anyone wishes to reduce these words to the form of a definition, he may say: "faith is a habit of the mind, whereby eternal life is begun in us, and which causes the intellect to assent to things not seen."

Thus faith is distinguished from everything else that pertains to the intellect. By what is meant by "evidence," it is distinguished from opinion, suspicion, and doubt, whereby the intellect does not adhere firmly to anything. By what is meant by "things not seen", it is distinguished from science and understanding, through which a thing becomes seen. As "the substance of things hoped for," the virtue of faith is also distinguished from what is commonly called faith, but is not directed to the hope of blessedness.

All other definitions of faith are explanations of that given by the apostle. The definitions given by Augustine {Tract.79 in Joan: 2 Quaest. Evang., Q.39): "faith is the virtue by which we believe things not seen," by the Damascene (4 De Fid. Orth.12): "faith is assent without inquiry," and by others: "faith is certainty of mind concerning things which are absent, more than opinion, but less than science," affirm what the apostle means by "the evidence of things not seen." The definition given by Dionysius (7 Div. Nom., lect.5): "faith is the enduring foundation of believers, by which they are devoted to the truth, and the truth shown forth in them," affirms what he means by "the substance of things hoped for."

On the first point: "substance" does not here mean the highest genus as distinguished from other genera. It denotes that wherein every genus bears a likeness to a substance, in that what is primary therein virtually contains the rest, and is accordingly said to be the substance of the rest.

On the second point: since faith pertains to the intellect as commanded by the will, the end of faith must include the objects of the virtues by which the will is perfected. Now hope is one of these virtues, as we shall show in Q.18, Art.1, and its object is included in the definition for this reason.

On the third point: love can be of things seen as well as of things not seen, and of things present as well as of things absent. Things loved are therefore not so appropriate to faith as things hoped for, since hope is always for the absent and unseen.

On the fourth point: as they are used in the definition, "substance" and "evidence" do not mean different genera, nor even different acts. They indicate different relations of the same act to different objects, as is plain from what we have said.

On the first point: when evidence is drawn from the proper principles of something, it causes the thing itself to be seen. But the evidence of divine authority does not make the thing itself to be seen, and such is the evidence of which the definition speaks.

[56] or "proportionately."