[II-II.q.4.a.1.arg.1] It would seem that the Apostle gives an unfitting definition of faith (Hebrews 11:1) when he says: "Faith is the substance of things to be hoped for, the evidence of things that appear not." For no quality is a substance: whereas faith is a quality, since it is a theological virtue, as stated above (I-II, 62, 3). Therefore it is not a substance.

[II-II.q.4.a.1.arg.2] Further, different virtues have different objects. Now things to be hoped for are the object of hope. Therefore they should not be included in a definition of faith, as though they were its object.

[II-II.q.4.a.1.arg.3] Further, faith is perfected by charity rather than by hope, since charity is the form of faith, as we shall state further on (3). Therefore the definition of faith should have included the thing to be loved rather than the thing to be hoped for.

[II-II.q.4.a.1.arg.4] Further, the same thing should not be placed in different genera. Now "substance" and "evidence" are different genera, and neither is subalternate to the other. Therefore it is unfitting to state that faith is both "substance" and "evidence."

[II-II.q.4.a.1.arg.5] Further, evidence manifests the truth of the matter for which it is adduced. Now a thing is said to be apparent when its truth is already manifest. Therefore it seems to imply a contradiction to speak of "evidence of things that appear not": and so faith is unfittingly defined.

[II-II.q.4.a.1.sc] The authority of the Apostle suffices.

[II-II.q.4.a.1.co] Though some say that the above words of the Apostle are not a definition of faith, yet if we consider the matter aright, this definition overlooks none of the points in reference to which faith can be defined, albeit the words themselves are not arranged in the form of a definition, just as the philosophers touch on the principles of the syllogism, without employing the syllogistic form.

In order to make this clear, we must observe that since habits are known by their acts, and acts by their objects, faith, being a habit, should be defined by its proper act in relation to its proper object. Now the act of faith is to believe, as stated above (2, 2,3), which is an act of the intellect determinate to one object of the will's command. Hence an act of faith is related both to the object of the will, i.e. to the good and the end, and to the object of the intellect, i.e. to the true. And since faith, through being a theological virtues, as stated above (I-II, 62, 2), has one same thing for object and end, its object and end must, of necessity, be in proportion to one another. Now it has been already stated (1, 1,4) that the object of faith is the First Truth, as unseen, and whatever we hold on account thereof: so that it must needs be under the aspect of something unseen that the First Truth is the end of the act of faith, which aspect is that of a thing hoped for, according to the Apostle (Romans 8:25): "We hope for that which we see not": because to see the truth is to possess it. Now one hopes not for what one has already, but for what one has not, as stated above (I-II, 67, 4). Accordingly the relation of the act of faith to its end which is the object of the will, is indicated by the words: "Faith is the substance of things to be hoped for." For we are wont to call by the name of substance, the first beginning of a thing, especially when the whole subsequent thing is virtually contained in the first beginning; for instance, we might say that the first self-evident principles are the substance of science, because, to wit, these principles are in us the first beginnings of science, the whole of which is itself contained in them virtually. On this way then faith is said to be the "substance of things to be hoped for," for the reason that in us the first beginning of things to be hoped for is brought about by the assent of faith, which contains virtually all things to be hoped for. Because we hope to be made happy through seeing the unveiled truth to which our faith cleaves, as was made evident when we were speaking of happiness (I-II, 3, 8; I-II, 4, 3).

The relationship of the act of faith to the object of the intellect, considered as the object of faith, is indicated by the words, "evidence of things that appear not," where "evidence" is taken for the result of evidence. For evidence induces the intellect to adhere to a truth, wherefore the firm adhesion of the intellect to the non-apparent truth of faith is called "evidence" here. Hence another reading has "conviction," because to wit, the intellect of the believer is convinced by Divine authority, so as to assent to what it sees not. Accordingly if anyone would reduce the foregoing words to the form of a definition, he may say that "faith is a habit of the mind, whereby eternal life is begun in us, making the intellect assent to what is non-apparent."

In this way faith is distinguished from all other things pertaining to the intellect. For when we describe it as "evidence," we distinguish it from opinion, suspicion, and doubt, which do not make the intellect adhere to anything firmly; when we go on to say, "of things that appear not," we distinguish it from science and understanding, the object of which is something apparent; and when we say that it is "the substance of things to be hoped for," we distinguish the virtue of faith from faith commonly so called, which has no reference to the beatitude we hope for.

Whatever other definitions are given of faith, are explanations of this one given by the Apostle. For when Augustine says (Tract. xl in Joan.: QQ. Evang. ii, qu. 39) that "faith is a virtue whereby we believe what we do not see," and when Damascene says (De Fide Orth. iv, 11) that "faith is an assent without research," and when others say that "faith is that certainty of the mind about absent things which surpasses opinion but falls short of science," these all amount to the same as the Apostle's words: "Evidence of things that appear not"; and when Dionysius says (Div. Nom. vii) that "faith is the solid foundation of the believer, establishing him in the truth, and showing forth the truth in him," comes to the same as "substance of things to be hoped for."

[II-II.q.4.a.1.ad.1] "Substance" here does not stand for the supreme genus condivided with the other genera, but for that likeness to substance which is found in each genus, inasmuch as the first thing in a genus contains the others virtually and is said to be the substance thereof.

[II-II.q.4.a.1.ad.2] Since faith pertains to the intellect as commanded by the will, it must needs be directed, as to its end, to the objects of those virtues which perfect the will, among which is hope, as we shall prove further on (18, 1). For this reason the definition of faith includes the object of hope.

[II-II.q.4.a.1.ad.3] Love may be of the seen and of the unseen, of the present and of the absent. Consequently a thing to be loved is not so adapted to faith, as a thing to be hoped for, since hope is always of the absent and the unseen.

[II-II.q.4.a.1.ad.4] "Substance" and "evidence" as included in the definition of faith, do not denote various genera of faith, nor different acts, but different relationships of one act to different objects, as is clear from what has been said.

[II-II.q.4.a.1.ad.5] Evidence taken from the proper principles of a thing, make it apparent, whereas evidence taken from Divine authority does not make a thing apparent in itself, and such is the evidence referred to in the definition of faith.

[II-II.q.4.a.2.arg.1] It would seem that faith does not reside in the intellect. For Augustine says (De Praedest. Sanct. v) that "faith resides in the believer's will." Now the will is a power distinct from the intellect. Therefore faith does not reside in the intellect.

[II-II.q.4.a.2.arg.2] Further, the assent of faith to believe anything, proceeds from the will obeying God. Therefore it seems that faith owes all its praise to obedience. Now obedience is in the will. Therefore faith is in the will, and not in the intellect.

[II-II.q.4.a.2.arg.3] Further, the intellect is either speculative or practical. Now faith is not in the speculative intellect, since this is not concerned with things to be sought or avoided, as stated in De Anima iii, 9, so that it is not a principle of operation, whereas "faith . . . worketh by charity" (Galatians 5:6). Likewise, neither is it in the practical intellect, the object of which is some true, contingent thing, that can be made or done. For the object of faith is the Eternal Truth, as was shown above (Question 1, Article 1). Therefore faith does not reside in the intellect.

[II-II.q.4.a.2.sc] Faith is succeeded by the heavenly vision, according to 1 Corinthians 13:12: "We see now through a glass in a dark manner; but then face to face." Now vision is in the intellect. Therefore faith is likewise.

[II-II.q.4.a.2.co] Since faith is a virtue, its act must needs be perfect. Now, for the perfection of an act proceeding from two active principles, each of these principles must be perfect: for it is not possible for a thing to be sawn well, unless the sawyer possess the art, and the saw be well fitted for sawing. Now, in a power of the soul, which is related to opposite objects, a disposition to act well is a habit, as stated above (I-II, 49, 4, ad 1,2,3). Wherefore an act that proceeds from two such powers must be perfected by a habit residing in each of them. Again, it has been stated above (2, 1,2) that to believe is an act of the intellect inasmuch as the will moves it to assent. And this act proceeds from the will and the intellect, both of which have a natural aptitude to be perfected in this way. Consequently, if the act of faith is to be perfect, there needs to be a habit in the will as well as in the intellect: even as there needs to be the habit of prudence in the reason, besides the habit of temperance in the concupiscible faculty, in order that the act of that faculty be perfect. Now, to believe is immediately an act of the intellect, because the object of that act is "the true," which pertains properly to the intellect. Consequently faith, which is the proper principle of that act, must needs reside in the intellect.

[II-II.q.4.a.2.ad.1] Augustine takes faith for the act of faith, which is described as depending on the believer's will, in so far as his intellect assents to matters of faith at the command of the will.

[II-II.q.4.a.2.ad.2] Not only does the will need to be ready to obey but also the intellect needs to be well disposed to follow the command of the will, even as the concupiscible faculty needs to be well disposed in order to follow the command of reason; hence there needs to be a habit of virtue not only in the commanding will but also in the assenting intellect.

[II-II.q.4.a.2.ad.3] Faith resides in the speculative intellect, as evidenced by its object. But since this object, which is the First Truth, is the end of all our desires and actions, as Augustine proves (De Trin. i, 8), it follows that faith worketh by charity just as "the speculative intellect becomes practical by extension" (De Anima iii, 10).

[II-II.q.4.a.3.arg.1] It would seem that charity is not the form of faith. For each thing derives its species from its form. When therefore two things are opposite members of a division, one cannot be the form of the other. Now faith and charity are stated to be opposite members of a division, as different species of virtue (1 Corinthians 13:13). Therefore charity is not the form of faith.

[II-II.q.4.a.3.arg.2] Further, a form and the thing of which it is the form are in one subject, since together they form one simply. Now faith is in the intellect, while charity is in the will. Therefore charity is not the form of faith.

[II-II.q.4.a.3.arg.3] Further, the form of a thing is a principle thereof. Now obedience, rather than charity, seems to be the principle of believing, on the part of the will, according to Romans 1:5: "For obedience to the faith in all nations." Therefore obedience rather than charity, is the form of faith.

[II-II.q.4.a.3.sc] Each thing works through its form. Now faith works through charity. Therefore the love of charity is the form of faith.

[II-II.q.4.a.3.co] As appears from what has been said above (I-II, 1, 3; I-II, 18, 6), voluntary acts take their species from their end which is the will's object. Now that which gives a thing its species, is after the manner of a form in natural things. Wherefore the form of any voluntary act is, in a manner, the end to which that act is directed, both because it takes its species therefrom, and because the mode of an action should correspond proportionately to the end. Now it is evident from what has been said (1), that the act of faith is directed to the object of the will, i.e. the good, as to its end: and this good which is the end of faith, viz. the Divine Good, is the proper object of charity. Therefore charity is called the form of faith in so far as the act of faith is perfected and formed by charity.

[II-II.q.4.a.3.ad.1] Charity is called the form of faith because it quickens the act of faith. Now nothing hinders one act from being quickened by different habits, so as to be reduced to various species in a certain order, as stated above (I-II, 18, 6,7; I-II, 61, 2) when we were treating of human acts in general.

[II-II.q.4.a.3.ad.2] This objection is true of an intrinsic form. But it is not thus that charity is the form of faith, but in the sense that it quickens the act of faith, as explained above.

[II-II.q.4.a.3.ad.3] Even obedience, and hope likewise, and whatever other virtue might precede the act of faith, is quickened by charity, as we shall show further on (23, 8), and consequently charity is spoken of as the form of faith.

[II-II.q.4.a.4.arg.1] It would seem that lifeless faith does not become living, or living faith lifeless. For, according to 1 Corinthians 13:10, "when that which is perfect is come, that which is in part shall be done away." Now lifeless faith is imperfect in comparison with living faith. Therefore when living faith comes, lifeless faith is done away, so that they are not one identical habit.

[II-II.q.4.a.4.arg.2] Further, a dead thing does not become a living thing. Now lifeless faith is dead, according to James 2:20: "Faith without works is dead." Therefore lifeless faith cannot become living.

[II-II.q.4.a.4.arg.3] Further, God's grace, by its advent, has no less effect in a believer than in an unbeliever. Now by coming to an unbeliever it causes the habit of faith. Therefore when it comes to a believer, who hitherto had the habit of lifeless faith, it causes another habit of faith in him.

[II-II.q.4.a.4.arg.4] Further, as Boethius says (In Categ. Arist. i), "accidents cannot be altered." Now faith is an accident. Therefore the same faith cannot be at one time living, and at another, lifeless.

[II-II.q.4.a.4.sc] A gloss on the words, "Faith without works is dead" (James 2:20) adds, "by which it lives once more." Therefore faith which was lifeless and without form hitherto, becomes formed and living.

[II-II.q.4.a.4.co] There have been various opinions on this question. For some [William of Auxerre, Sum. Aur. III, iii, 15 have said that living and lifeless faith are distinct habits, but that when living faith comes, lifeless faith is done away, and that, in like manner, when a man sins mortally after having living faith, a new habit of lifeless faith is infused into him by God. But it seems unfitting that grace should deprive man of a gift of God by coming to him, and that a gift of God should be infused into man, on account of a mortal sin.

Consequently others [Alexander of Hales, Sum. Theol. iii, 64 have said that living and lifeless faith are indeed distinct habits, but that, all the same, when living faith comes the habit of lifeless faith is not taken away, and that it remains together with the habit of living faith in the same subject. Yet again it seems unreasonable that the habit of lifeless faith should remain inactive in a person having living faith.

We must therefore hold differently that living and lifeless faith are one and the same habit. The reason is that a habit is differentiated by that which directly pertains to that habit. Now since faith is a perfection of the intellect, that pertains directly to faith, which pertains to the intellect. Again, what pertains to the will, does not pertain directly to faith, so as to be able to differentiate the habit of faith. But the distinction of living from lifeless faith is in respect of something pertaining to the will, i.e. charity, and not in respect of something pertaining to the intellect. Therefore living and lifeless faith are not distinct habits.

[II-II.q.4.a.4.ad.1] The saying of the Apostle refers to those imperfect things from which imperfection is inseparable, for then, when the perfect comes the imperfect must needs be done away. Thus with the advent of clear vision, faith is done away, because it is essentially "of the things that appear not." When, however, imperfection is not inseparable from the imperfect thing, the same identical thing which was imperfect becomes perfect. Thus childhood is not essential to man and consequently the same identical subject who was a child, becomes a man. Now lifelessness is not essential to faith, but is accidental thereto as stated above. Therefore lifeless faith itself becomes living.

[II-II.q.4.a.4.ad.2] That which makes an animal live is inseparable from an animal, because it is its substantial form, viz. the soul: consequently a dead thing cannot become a living thing, and a living and a dead thing differ specifically. On the other hand that which gives faith its form, or makes it live, is not essential to faith. Hence there is no comparison.

[II-II.q.4.a.4.ad.3] Grace causes faith not only when faith begins anew to be in a man, but also as long as faith lasts. For it has been said above (I, 104, 1; I-II, 109, 9) that God is always working man's justification, even as the sun is always lighting up the air. Hence grace is not less effective when it comes to a believer than when it comes to an unbeliever: since it causes faith in both, in the former by confirming and perfecting it, in the latter by creating it anew.

We might also reply that it is accidental, namely on account of the disposition of the subject, that grace does not cause faith in one who has it already: just as, on the other hand, a second mortal sin does not take away grace from one who has already lost it through a previous mortal sin.

[II-II.q.4.a.4.ad.4] When living faith becomes lifeless, faith is not changed, but its subject, the soul, which at one time has faith without charity, and at another time, with charity.

[II-II.q.4.a.5.arg.1] It would seem that faith is not a virtue. For virtue is directed to the good, since "it is virtue that makes its subject good," as the Philosopher states (Ethic. ii, 6). But faith is directed to the true. Therefore faith is not a virtue.

[II-II.q.4.a.5.arg.2] Further, infused virtue is more perfect than acquired virtue. Now faith, on account of its imperfection, is not placed among the acquired intellectual virtues, as the Philosopher states (Ethic. vi, 3). Much less, therefore, can it be considered an infused virtue.

[II-II.q.4.a.5.arg.3] Further, living and lifeless faith are the same species, as stated above (Article 4). Now lifeless faith is not a virtue, since it is not connected with the other virtues. Therefore neither is living faith a virtue.

[II-II.q.4.a.5.sc] Man is justified by the virtues, since "justice is all virtue," as the Philosopher states (Ethic. v, 1). Now man is justified by faith according to Romans 5:1: "Being justified therefore by faith let us have peace," etc. Therefore faith is a virtue.

[II-II.q.4.a.5.co] As shown above, it is by human virtue that human acts are rendered good; hence, any habit that is always the principle of a good act, may be called a human virtue. Such a habit is living faith. For since to believe is an act of the intellect assenting to the truth at the command of the will, two things are required that this act may be perfect: one of which is that the intellect should infallibly tend to its object, which is the true; while the other is that the will should be infallibly directed to the last end, on account of which it assents to the true: and both of these are to be found in the act of living faith. For it belongs to the very essence of faith that the intellect should ever tend to the true, since nothing false can be the object of faith, as proved above (Question 1, Article 3): while the effect of charity, which is the form of faith, is that the soul ever has its will directed to a good end. Therefore living faith is a virtue.

On the other hand, lifeless faith is not a virtue, because, though the act of lifeless faith is duly perfect on the part of the intellect, it has not its due perfection as regards the will: just as if temperance be in the concupiscible, without prudence being in the rational part, temperance is not a virtue, as stated above (I-II, 65, 1), because the act of temperance requires both an act of reason, and an act of the concupiscible faculty, even as the act of faith requires an act of the will, and an act of the intellect.

[II-II.q.4.a.5.ad.1] The truth is itself the good of the intellect, since it is its perfection: and consequently faith has a relation to some good in so far as it directs the intellect to the true. Furthermore, it has a relation to the good considered as the object of the will, inasmuch as it is formed by charity.

[II-II.q.4.a.5.ad.2] The faith of which the Philosopher speaks is based on human reasoning in a conclusion which does not follow, of necessity, from its premisses; and which is subject to be false: hence such like faith is not a virtue. On the other hand, the faith of which we are speaking is based on the Divine Truth, which is infallible, and consequently its object cannot be anything false; so that faith of this kind can be a virtue.

[II-II.q.4.a.5.ad.3] Living and lifeless faith do not differ specifically, as though they belonged to different species. But they differ as perfect and imperfect within the same species. Hence lifeless faith, being imperfect, does not satisfy the conditions of a perfect virtue, for "virtue is a kind of perfection" (Phys. vii, text. 18).

[II-II.q.4.a.6.arg.1] It would seem that faith is not one. For just as faith is a gift of God according to Ephesians 2:8, so also wisdom and knowledge are numbered among God's gifts according to Isaiah 11:2. Now wisdom and knowledge differ in this, that wisdom is about eternal things, and knowledge about temporal things, as Augustine states (De Trin. xii, 14,15). Since, then, faith is about eternal things, and also about some temporal things, it seems that faith is not one virtue, but divided into several parts.

[II-II.q.4.a.6.arg.2] Further, confession is an act of faith, as stated above (Question 3, Article 1). Now confession of faith is not one and the same for all: since what we confess as past, the fathers of old confessed as yet to come, as appears from Isaiah 7:14: "Behold a virgin shall conceive." Therefore faith is not one.

[II-II.q.4.a.6.arg.3] Further, faith is common to all believers in Christ. But one accident cannot be in many subjects. Therefore all cannot have one faith.

[II-II.q.4.a.6.sc] The Apostle says (Ephesians 4:5): "One Lord, one faith."

[II-II.q.4.a.6.co] If we take faith as a habit, we can consider it in two ways. First on the part of the object, and thus there is one faith. Because the formal object of faith is the First Truth, by adhering to which we believe whatever is contained in the faith. Secondly, on the part of the subject, and thus faith is differentiated according as it is in various subjects. Now it is evident that faith, just as any other habit, takes its species from the formal aspect of its object, but is individualized by its subject. Hence if we take faith for the habit whereby we believe, it is one specifically, but differs numerically according to its various subjects.

If, on the other hand, we take faith for that which is believed, then, again, there is one faith, since what is believed by all is one same thing: for though the things believed, which all agree in believing, be diverse from one another, yet they are all reduced to one.

[II-II.q.4.a.6.ad.1] Temporal matters which are proposed to be believed, do not belong to the object of faith, except in relation to something eternal, viz. the First Truth, as stated above (Question 1, Article 1). Hence there is one faith of things both temporal and eternal. It is different with wisdom and knowledge, which consider temporal and eternal matters under their respective aspects.

[II-II.q.4.a.6.ad.2] This difference of past and future arises, not from any difference in the thing believed, but from the different relationships of believers to the one thing believed, as also we have mentioned above (I-II, 103, 4; I-II, 107, 1, ad 1).

[II-II.q.4.a.6.ad.3] This objection considers numerical diversity of faith.