Thomas Aquinas

“ 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. ”

“ Art. 3 - Whether a man is bound to give thanks to every benefactor? 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 Ecclus. 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.
Objection 2: Further, gratitude is a repayment of an act of grace. ”

“ 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." ”

“ 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. ”

“ 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? ”

“ 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. ”

“ A [5] ) , 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. ”