Summa Th. II-II EN Qu.104 a.6
Objection: 1. It seems that Christians are not bound to obey the secular power. For a gloss on Mt 17,25, "Then the children are free," says: "If in every kingdom the children of the king who holds sway over that kingdom are free, then the children of that King, under Whose sway are all kingdoms, should be free in every kingdom." Now Christians, by their faith in Christ, are made children of God, according to Jn 1,12: "He gave them power to be made the sons of God, to them that believe in His name." Therefore they are not bound to obey the secular power.
2. Further, it is written (Rm 7,4): "You . . . are become dead to the law by the body of Christ," and the law mentioned here is the divine law of the Old Testament. Now human law whereby men are subject to the secular power is of less account than the divine law of the Old Testament. Much more, therefore, since they have become members of Christ's body, are men freed from the law of subjection, whereby they were under the power of secular princes.
3. Further, men are not bound to obey robbers, who oppress them with violence. Now, Augustine says (De Civ. Dei iv): "Without justice, what else is a kingdom but a huge robbery?" Since therefore the authority of secular princes is frequently exercised with injustice, or owes its origin to some unjust usurpation, it seems that Christians ought not to obey secular princes.
On the contrary It is written (Titus 3:1): "Admonish them to be subject to princes and powers," and (1P 2,13-14): "Be ye subject . . . to every human creature for God's sake: whether it be to the king as excelling, or to governors as sent by him."
I answer that Faith in Christ is the origin and cause of justice, according to Rm 3,22, "The justice of God by faith of Jesus Christ:" wherefore faith in Christ does not void the order of justice, but strengthens it." Now the order of justice requires that subjects obey their superiors, else the stability of human affairs would cease. Hence faith in Christ does not excuse the faithful from the obligation of obeying secular princes.
Reply to Objection: 1. As stated above (Article ), subjection whereby one man is bound to another regards the body; not the soul, which retains its liberty. Now, in this state of life we are freed by the grace of Christ from defects of the soul, but not from defects of the body, as the Apostle declares by saying of himself (Rm 7,23) that in his mind he served the law of God, but in his flesh the law of sin. Wherefore those that are made children of God by grace are free from the spiritual bondage of sin, but not from the bodily bondage, whereby they are held bound to earthly masters, as a gloss observes on 1Tm 6,1, "Whosoever are servants under the yoke," etc.
2. The Old Law was a figure of the New Testament, and therefore it had to cease on the advent of truth. And the comparison with human law does not stand because thereby one man is subject to another. Yet man is bound by divine law to obey his fellow-man.
3. Man is bound to obey secular princes in so far as this is required by order of justice. Wherefore if the prince's authority is not just but usurped, or if he commands what is unjust, his subjects are not bound to obey him, except perhaps accidentally, in order to avoid scandal or danger.
We must now consider disobedience, under which head there are two points of inquiry:
(1) Whether it is a mortal sin?
(2) Whether it is the most grievous of sins?
Objection: 1. It seems that disobedience is not a mortal sin. For every sin is a disobedience, as appears from Ambrose's definition given above (Question , Article , Objection ). Therefore if disobedience were a mortal sin, every sin would be mortal.
2. Further, Gregory says (Moral. xxxi) that disobedience is born of vainglory. But vainglory is not a mortal sin. Neither therefore is disobedience.
3. Further, a person is said to be disobedient when he does not fulfil a superior's command. But superiors often issue so many commands that it is seldom, if ever, possible to fulfil them. Therefore if disobedience were a mortal sin, it would follow that man cannot avoid mortal sin, which is absurd. Wherefore disobedience is not a mortal sin.
On the contrary The sin of disobedience to parents is reckoned (Rm 1,30 2Tm 3,2) among other mortal sins.
I answer that As stated above (Question , Article ; I-II 72,5; I-II 88,1), a mortal sin is one that is contrary to charity which is the cause of spiritual life. Now by charity we love God and our neighbor. The charity of God requires that we obey His commandments, as stated above (Question , Article ). Therefore to be disobedient to the commandments of God is a mortal sin, because it is contrary to the love of God.Again, the commandments of God contain the precept of obedience to superiors. Wherefore also disobedience to the commands of a superior is a mortal sin, as being contrary to the love of God, according to Rm 13,2, "He that resisteth the power, resisteth the ordinance of God." It is also contrary to the love of our neighbor, as it withdraws from the superior who is our neighbor the obedience that is his due.
Reply to Objection: 1. The definition given by Ambrose refers to mortal sin, which has the character of perfect sin. Venial sin is not disobedience, because it is not contrary to a precept, but beside it. Nor again is every mortal sin disobedience, properly and essentially, but only when one contemns a precept, since moral acts take their species from the end. And when a thing is done contrary to a precept, not in contempt of the precept, but with some other purpose, it is not a sin of disobedience except materially, and belongs formally to another species of sin.
2. Vainglory desires display of excellence. And since it seems to point to a certain excellence that one be not subject to another's command, it follows that disobedience arises from vainglory. But there is nothing to hinder mortal sin from arising out of venial sin, since venial sin is a disposition to mortal.
3. No one is bound to do the impossible: wherefore if a superior makes a heap of precepts and lays them upon his subjects, so that they are unable to fulfil them, they are excused from sin. Wherefore superiors should refrain from making a multitude of precepts.
Objection: 1. It seems that disobedience is the most grievous of sins. For it is written (1S 15,23): "It is like the sin of witchcraft to rebel, and like the crime of idolatry to refuse to obey." But idolatry is the most grievous of sins, as stated above (Question , Article ). Therefore disobedience is the most grievous of sins.
2. Further, the sin against the Holy Ghost is one that removes the obstacles of sin, as stated above (Question , Article ). Now disobedience makes a man contemn a precept which, more than anything, prevents a man from sinning. Therefore disobedience is a sin against the Holy Ghost, and consequently is the most grievous of sins.
3. Further, the Apostle says (Rm 5,19) that "by the disobedience of one man, many were made sinners." Now the cause is seemingly greater than its effect. Therefore disobedience seems to be a more grievous sin than the others that are caused thereby.
On the contrary Contempt of the commander is a more grievous sin than contempt of his command. Now some sins are against the very person of the commander, such as blasphemy and murder. Therefore disobedience is not the most grievous of sins.
I answer that Not every disobedience is equally a sin: for one disobedience may be greater than another, in two ways. First, on the part of the superior commanding, since, although a man should take every care to obey each superior, yet it is a greater duty to obey a higher than a lower authority, in sign of which the command of a lower authority is set aside if it be contrary to the command of a higher authority. Consequently the higher the person who commands, the more grievous is it to disobey him: so that it is more grievous to disobey God than man. Secondly, on the part of the things commanded. For the person commanding does not equally desire the fulfilment of all his commands: since every such person desires above all the end, and that which is nearest to the end. Wherefore disobedience is the more grievous, according as the unfulfilled commandment is more in the intention of the person commanding. As to the commandments of God, it is evident that the greater the good commanded, the more grievous the disobedience of that commandment, because since God's will is essentially directed to the good, the greater the good the more does God wish it to be fulfilled. Consequently he that disobeys the commandment of the love of God sins more grievously than one who disobeys the commandment of the love of our neighbor. On the other hand, man's will is not always directed to the greater good: hence, when we are bound by a mere precept of man, a sin is more grievous, not through setting aside a greater good, but through setting aside that which is more in the intention of the person commanding.Accordingly the various degrees of disobedience must correspond with the various degrees of precepts: because the disobedience in which there is contempt of God's precept, from the very nature of disobedience is more grievous than a sin committed against a man, apart from the latter being a disobedience to God. And I say this because whoever sins against his neighbor acts also against God's commandment. And if the divine precept be contemned in a yet graver matter, the sin is still more grievous. The disobedience that contains contempt of a man's precept is less grievous than the sin which contemns the man who made the precept, because reverence for the person commanding should give rise to reverence for his command. In like manner a sin that directly involves contempt of God, such as blasphemy, or the like, is more grievous (even if we mentally separate the disobedience from the sin) than would be a sin involving contempt of God's commandment alone.
Reply to Objection: 1. This comparison of Samuel is one, not of equality but of likeness, because disobedience redounds to the contempt of God just as idolatry does, though the latter does so more.
2. Not every disobedience is sin against the Holy Ghost, but only that which obstinacy is added: for it is not the contempt of any obstacle to sin that constitutes sin against the Holy Ghost, else the contempt of any good would be a sin against the Holy Ghost, since any good may hinder a man from committing sin. The sin against the Holy Ghost consists in the contempt of those goods which lead directly to repentance and the remission of sins.
3. The first sin of our first parent, from which sin was transmitted to a men, was not disobedience considered as a special sin, but pride, from which then man proceeded to disobey. Hence the Apostle in these words seems to take disobedience in its relation to every sin.
We must now consider thankfulness or gratitude, and ingratitude. Concerning thankfulness there are six points of inquiry:
(1) Whether thankfulness is a special virtue distinct from other virtues?
(2) Who owes more thanks to God, the innocent or the penitent?
(3) Whether man is always bound to give thanks for human favors?
(4) Whether thanksgiving should be deferred?
(5) Whether thanksgiving should be measured according to the favor received or the disposition of the giver?
(6) Whether one ought to pay back more than one has received?
Objection: 1. It seems that thankfulness is not a special virtue, distinct from other virtue. For we have received the greatest benefits from God, and from our parents. Now the honor which we pay to God in return belongs to the virtue of religion, and the honor with which we repay our parents belongs to the virtue of piety. Therefore thankfulness or gratitude is not distinct from the other virtues.
2. Further, proportionate repayment belongs to commutative justice, according to the Philosopher (Ethic. v, 4). Now the purpose of giving thanks is repayment (Ethic. 5,4). Therefore thanksgiving, which belongs to gratitude, is an act of justice. Therefore gratitude is not a special virtue, distinct from other virtues.
3. Further, acknowledgment of favor received is requisite for the preservation of friendship, according to the Philosopher (Ethic. viii, 13; ix, 1). Now friendship is associated with all the virtues, since they are the reason for which man is loved. Therefore thankfulness or gratitude, to which it belongs to repay favors received, is not a special virtue.
On the contrary Tully reckons thankfulness a special part of justice (De Invent. Rhet. ii).
I answer that As stated above (I-II 60,3), the nature of the debt to be paid must needs vary according to various causes giving rise to the debt, yet so that the greater always includes the lesser. Now the cause of debt is found primarily and chiefly in God, in that He is the first principle of all our goods: secondarily it is found in our father, because he is the proximate principle of our begetting and upbringing: thirdly it is found in the person that excels in dignity, from whom general favors proceed; fourthly it is found in a benefactor, from whom we have received particular and private favors, on account of which we are under particular obligation to him.Accordingly, since what we owe God, or our father, or a person excelling in dignity, is not the same as what we owe a benefactor from whom we have received some particular favor, it follows that after religion, whereby we pay God due worship, and piety, whereby we worship our parents, and observance, whereby we worship persons excelling in dignity, there is thankfulness or gratitude, whereby we give thanks to our benefactors. And it is distinct from the foregoing virtues, just as each of these is distinct from the one that precedes, as falling short thereof.
Reply to Objection: 1. Just as religion is superexcelling piety, so is it excelling thankfulness or gratitude: wherefore giving thanks to God was reckoned above (Question , Article ) among things pertaining to religion.
2. Proportionate repayment belongs to commutative justice, when it answers to the legal due; for instance when it is contracted that so much be paid for so much. But the repayment that belongs to the virtue of thankfulness or gratitude answers to the moral debt, and is paid spontaneously. Hence thanksgiving is less thankful when compelled, as Seneca observes (De Beneficiis iii).
3. Since true friendship is based on virtue, whatever there is contrary to virtue in a friend is an obstacle to friendship, and whatever in him is virtuous is an incentive to friendship. In this way friendship is preserved by repayment of favors, although repayment of favors belongs specially to the virtue of gratitude.
Objection: 1. It seems that the innocent is more bound to give thanks to God than the penitent. For the greater the gift one has received from God, the more one is bound to give Him thanks. Now the gift of innocence is greater than that of justice restored. Therefore it seems that the innocent is more bound to give thanks to God than the penitent.
2. Further, a man owes love to his benefactor just as he owes him gratitude. Now Augustine says (Confess. ii): "What man, weighing his own infirmity, would dare to ascribe his purity and innocence to his own strength; that so he should love Thee the less, as if he had less needed Thy mercy, whereby Thou remittest sins to those that turn to Thee?" And farther on he says: "And for this let him love Thee as much, yea and more, since by Whom he sees me to have been recovered from such deep torpor of sin, by Him he sees himself to have been from the like torpor of sin preserved." Therefore the innocent is also more bound to give thanks than the penitent.
3. Further, the more a gratuitous favor is continuous, the greater the thanksgiving due for it. Now the favor of divine grace is more continuous in the innocent than in the penitent. For Augustine says (Confess. iii): "To Thy grace I ascribe it, and to Thy mercy, that Thou hast melted away my sins as it were ice. To Thy grace I ascribe also whatsoever I have not done of evil; for what might I not have done? . . . Yea, all I confess to have been forgiven me, both what evils I committed by my own wilfulness, and what by Thy guidance committed not." Therefore the innocent is more bound to give thanks than the penitent.
On the contrary It is written (Lc 7,43): "To whom more is forgiven, he loveth more [*Vulg.: 'To whom less is forgiven, he loveth less' Lc 7,47]." Therefore for the same reason he is bound to greater thanksgiving.
I answer that Thanksgiving [gratiarum actio] in the recipient corresponds to the favor [gratia] of the giver: so that when there is greater favor on the part of the giver, greater thanks are due on the part of the recipient. Now a favor is something bestowed "gratis": wherefore on the part of the giver the favor may be greater on two counts. First, owing to the quantity of the thing given: and in this way the innocent owes greater thanksgiving, because he receives a greater gift from God, also, absolutely speaking, a more continuous gift, other things being equal. Secondly, a favor may be said to be greater, because it is given more gratuitously; and in this sense the penitent is more bound to give thanks than the innocent, because what he receives from God is more gratuitously given: since, whereas he was deserving of punishment, he has received grace. Wherefore, although the gift bestowed on the innocent is, considered absolutely, greater, yet the gift bestowed on the penitent is greater in relation to him: even as a small gift bestowed on a poor man is greater to him than a great gift is to a rich man. And since actions are about singulars, in matters of action, we have to take note of what is such here and now, rather than of what is such absolutely, as the Philosopher observes (Ethic. iii) in treating of the voluntary and the involuntary.
Reply to Objection: 1. This suffices for the Replies to the Objections.
Objection: 1. It seems that the a man is not bound to give thanks to every benefactor. For a man may benefit himself just as he may harm himself, according to Si 14,5, "He that is evil to himself, to whom will he be good?" But a man cannot thank himself, since thanksgiving seems to pass from one person to another. Therefore thanksgiving is not due to every benefactor.
2. Further, gratitude is a repayment of an act of grace. But some favors are granted without grace, and are rudely, slowly and grudgingly given. Therefore gratitude is not always due to a benefactor.
3. Further, no thanks are due to one who works for his own profit. But sometimes people bestow favors for their own profit. Therefore thanks are not due to them.
4. Further, no thanks are due to a slave, for all that he is belongs to his master. Yet sometimes a slave does a good turn to his master. Therefore gratitude is not due to every benefactor .
5. Further, no one is bound to do what he cannot do equitably and advantageously. Now it happens at times that the benefactor is very well off, and it would be of no advantage to him to be repaid for a favor he has bestowed. Again it happens sometimes that the benefactor from being virtuous has become wicked, so that it would not seem equitable to repay him. Also the recipient of a favor may be a poor man, and is quite unable to repay. Therefore seemingly a man is not always bound to repayment for favors received.
6. Further, no one is bound to do for another what is inexpedient and hurtful to him. Now sometimes it happens that repayment of a favor would be hurtful or useless to the person repaid. Therefore favors are not always to be repaid by gratitude.
On the contrary It is written (1Th 5,18): "In all things give thanks."
I answer that Every effect turns naturally to its cause; wherefore Dionysius says (Div. Nom. i) that "God turns all things to Himself because He is the cause of all": for the effect must needs always be directed to the end of the agent. Now it is evident that a benefactor, as such, is cause of the beneficiary. Hence the natural order requires that he who has received a favor should, by repaying the favor, turn to his benefactor according to the mode of each. And, as stated above with regard to a father (Question , Article ; Question , Article ), a man owes his benefactor, as such, honor and reverence, since the latter stands to him in the relation of principle; but accidentally he owes him assistance or support, if he need it.
Reply to Objection: 1. In the words of Seneca (1 Benef. v), "just as a man is liberal who gives not to himself but to others, and gracious who forgives not himself but others, and merciful who is moved, not by his own misfortunes but by another's, so too, no man confers a favor on himself, he is but following the bent of his nature, which moves him to resist what hurts him, and to seek what is profitable." Wherefore in things that one does for oneself, there is no place for gratitude or ingratitude, since a man cannot deny himself a thing except by keeping it. Nevertheless things which are properly spoken of in relation to others are spoken of metaphorically in relation to oneself, as the Philosopher states regarding justice (Ethic. v, 11), in so far, to wit, as the various parts of man are considered as though they were various persons.
2. It is the mark of a happy disposition to see good rather than evil. Wherefore if someone has conferred a favor, not as he ought to have conferred it, the recipient should not for that reason withhold his thanks. Yet he owes less thanks, than if the favor had been conferred duly, since in fact the favor is less, for, as Seneca remarks (De Benef. ii.) "promptness enhances, delay discounts a favor."
3. As Seneca observes (De Benef. vi), "it matters much whether a person does a kindness to us for his own sake, or for ours, or for both his and ours. He that considers himself only, and benefits because cannot otherwise benefit himself, seems to me like a man who seeks fodder for his cattle." And farther on: "If he has done it for me in common with himself, having both of us in his mind, I am ungrateful and not merely unjust, unless I rejoice that what was profitable to him is profitable to me also. It is the height of malevolence to refuse to recognize a kindness, unless the giver has been the loser thereby."
4. As Seneca observes (De Benef. iii), "when a slave does what is wont to be demanded of a slave, it is part of his service: when he does more than a slave is bound to do, it is a favor: for as soon as he does anything from a motive of friendship, if indeed that be his motive, it is no longer called service." Wherefore gratitude is due even to a slave, when he does more than his duty.
5. A poor man is certainly not ungrateful if he does what he can. For since kindness depends on the heart rather than on the deed, so too gratitude depends chiefly the heart. Hence Seneca says (De Benef. ii): "Who receives a favor gratefully, has already begun to pay it back: and that we are grateful for favors received should be shown by the outpourings of the heart, not only in his hearing but everywhere." From this it is evident that however well off a man may be, it is possible to thank him for his kindness by showing him reverence and honor. Wherefore the Philosopher says (Ethic. viii, 14): "He that abounds should be repaid with honor, he that is in want should be repaid with money": and Seneca writes (De Benef. vi): "There are many ways of repaying those who are well off, whatever we happen to owe them; such as good advice, frequent fellowship, affable and pleasant conversation without flattery." Therefore there is no need for a man to desire neediness or distress in his benefactor before repaying his kindness, because, as Seneca says (De Benef. vi), "it were inhuman to desire this in one from whom you have received no favor; how much more so to desire it in one whose kindness has made you his debtor!"If, however, the benefactor has lapsed from virtue, nevertheless he should be repaid according to his state, that he may return to virtue if possible. But if he be so wicked as to be incurable, then his heart has changed, and consequently no repayment is due for his kindness, as heretofore. And yet, as far as it possible without sin, the kindness he has shown should be held in memory, as the Philosopher says (Ethic. ix, 3).
6. As stated in the preceding reply, repayment of a favor depends chiefly on the affection of the heart: wherefore repayment should be made in such a way as to prove most beneficial. If, however, through the benefactor's carelessness it prove detrimental to him, this is not imputed to the person who repays him, as Seneca observes (De Benef. vii): "It is my duty to repay, and not to keep back and safeguard my repayment."
Objection: 1. It seems that a man is bound to repay a favor at once. For we are bound to restore at once what we owe, unless the term be fixed. Now there is no term prescribed for the repayment of favors, and yet this repayment is a duty, as stated above (Article ). Therefore a man is bound to repay a favor at once.
2. Further, a good action would seem to be all the more praiseworthy according as it is done with greater earnestness. Now earnestness seems to make a man do his duty without any delay. Therefore it is apparently more praiseworthy to repay a favor at once.
3. Further, Seneca says (De Benef. ii) that "it is proper to a benefactor to act freely and quickly." Now repayment ought to equal the favor received. Therefore it should be done at once.
On the contrary Seneca says (De Benef. iv): "He that hastens to repay, is animated with a sense, not of gratitude but of indebtedness."
I answer that Just as in conferring a favor two things are to be considered, namely, the affection of the heart and the gift, so also must these things be considered in repaying the favor. As regards the affection of the heart, repayment should be made at once, wherefore Seneca says (De Benef. ii): "Do you wish to repay a favor? Receive it graciously." As regards the gift, one ought to wait until such a time as will be convenient to the benefactor. In fact, if instead of choosing a convenient time, one wished to repay at once, favor for favor, it would not seem to be a virtuous, but a constrained repayment. For, as Seneca observes (De Benef. iv), "he that wishes to repay too soon, is an unwilling debtor, and an unwilling debtor is ungrateful."
Reply to Objection: 1. A legal debt must be paid at once, else the equality of justice would not be preserved, if one kept another's property without his consent. But a moral debt depends on the equity of the debtor: and therefore it should be repaid in due time according as the rectitude of virtue demands.
2. Earnestness of the will is not virtuous unless it be regulated by reason; wherefore it is not praiseworthy to forestall the proper time through earnestness.
3. Favors also should be conferred at a convenient time and one should no longer delay when the convenient time comes; and the same is to be observed in repaying favors.
Objection: 1. It seems that in repaying favors we should not look at the benefactor's disposition but at the deed. For repayment is due to beneficence, and beneficence consists in deeds, as the word itself denotes. Therefore in repaying favors we should look at the deed.
2. Further, thanksgiving, whereby we repay favors, is a part of justice. But justice considers equality between giving and taking. Therefore also in repaying favors we should consider the deed rather than the disposition of the benefactor.
3. Further, no one can consider what he does not know. Now God alone knows the interior disposition. Therefore it is impossible to repay a favor according to the benefactor's disposition.
On the contrary Seneca says (De Benef. i): "We are sometimes under a greater obligation to one who has given little with a large heart, and has bestowed a small favor, yet willingly."
I answer that The repayment of a favor may belong to three virtues, namely, justice, gratitude and friendship. It belongs to justice when the repayment has the character of a legal debt, as in a loan and the like: and in such cases repayment must be made according to the quantity received.On the other hand, repayment of a favor belongs, though in different ways, to friendship and likewise to the virtue of gratitude when it has the character of a moral debt. For in the repayment of friendship we have to consider the cause of friendship; so that in the friendship that is based on the useful, repayment should be made according to the usefulness accruing from the favor conferred, and in the friendship based on virtue repayment should be made with regard for the choice or disposition of the giver, since this is the chief requisite of virtue, as stated in Ethic. viii, 13. And likewise, since gratitude regards the favor inasmuch as it is bestowed gratis, and this regards the disposition of the giver, it follows again that repayment of a favor depends more on the disposition of the giver than on the effect.
Reply to Objection: 1. Every moral act depends on the will. Hence a kindly action, in so far as it is praiseworthy and is deserving of gratitude, consists materially in the thing done, but formally and chiefly in the will. Hence Seneca says (De Benef. i): "A kindly action consists not in deed or gift, but in the disposition of the giver or doer."
2. Gratitude is a part of justice, not indeed as a species is part of a genus, but by a kind of reduction to the genus of justice, as stated above (Question ). Hence it does not follow that we shall find the same kind of debt in both virtues.
3. God alone sees man's disposition in itself: but in so far as it is shown by certain signs, man also can know it. It is thus that a benefactor's disposition is known by the way in which he does the kindly action, for instance through his doing it joyfully and readily.
Objection: 1. It seems that there is no need for the repayment of gratitude to surpass the favor received. For it is not possible to make even equal repayment to some, for instance, one's parents, as the Philosopher states (Ethic. viii, 14). Now virtue does not attempt the impossible. Therefore gratitude for a favor does not tend to something yet greater.
2. Further, if one person repays another more than he has received by his favor, by that very fact he gives him something his turn, as it were. But the latter owes him repayment for the favor which in his turn the former has conferred on him. Therefore he that first conferred a favor will be bound to a yet greater repayment, and so on indefinitely. Now virtue does not strive at the indefinite, since "the indefinite removes the nature of good" (Metaph. ii, text. 8). Therefore repayment of gratitude should not surpass the favor received.
3. Further, justice consists in equality. But "more" is excess of equality. Since therefore excess is sinful in every virtue, it seems that to repay more than the favor received is sinful and opposed to justice.
On the contrary The Philosopher says (Ethic. v, 5): "We should repay those who are gracious to us, by being gracious to them return," and this is done by repaying more than we have received. Therefore gratitude should incline to do something greater.
I answer that As stated above (Article ), gratitude regards the favor received according the intention of the benefactor; who seems be deserving of praise, chiefly for having conferred the favor gratis without being bound to do so. Wherefore the beneficiary is under a moral obligation to bestow something gratis in return. Now he does not seem to bestow something gratis, unless he exceeds the quantity of the favor received: because so long as he repays less or an equivalent, he would seem to do nothing gratis, but only to return what he has received. Therefore gratitude always inclines, as far as possible, to pay back something more.
Reply to Objection: 1. As stated above (Article , ad 5; Article ), in repaying favors we must consider the disposition rather than the deed. Accordingly, if we consider the effect of beneficence, which a son receives from his parents namely, to be and to live, the son cannot make an equal repayment, as the Philosopher states (Ethic. viii, 14). But if we consider the will of the giver and of the repayer, then it is possible for the son to pay back something greater to his father, as Seneca declares (De Benef. iii). If, however, he were unable to do so, the will to pay back would be sufficient for gratitude.
2. The debt of gratitude flows from charity, which the more it is paid the more it is due, according to Rm 13,8, "Owe no man anything, but to love one another." Wherefore it is not unreasonable if the obligation of gratitude has no limit.
3. As in injustice, which is a cardinal virtue, we consider equality of things, so in gratitude we consider equality of wills. For while on the one hand the benefactor of his own free-will gave something he was not bound to give, so on the other hand the beneficiary repays something over and above what he has received.
Summa Th. II-II EN Qu.104 a.6