Summa Theologica, by St. Thomas Aquinas, [1947], at sacred-texts.com
We must now consider perseverance and the vices opposed to it. Under the head of perseverance there are four points of inquiry:
(1) Whether perseverance is a virtue?
(2) Whether it is a part of fortitude?
(3) Of its relation to constancy;
(4) Whether it needs the help of grace?
Objection 1: It seems that perseverance is not a virtue. For, according to the Philosopher (Ethic. vii, 7), continency is greater than perseverance. But continency is not a virtue, as stated in Ethic. iv, 9. Therefore perseverance is not a virtue.
Objection 2: Further, "by virtue man lives aright," according to Augustine (De Lib. Arb. ii, 19). Now according to the same authority (De Persever. i), no one can be said to have perseverance while living, unless he persevere until death. Therefore perseverance is not a virtue.
Objection 3: Further, it is requisite of every virtue that one should persist unchangeably in the work of that virtue, as stated in Ethic. ii, 4. But this is what we understand by perseverance: for Tully says (De Invent. Rhet. ii) that "perseverance is the fixed and continued persistence in a well-considered purpose." Therefore perseverance is not a special virtue, but a condition of every virtue.
On the contrary, Andronicus [*Chrysippus: in De Affect.] says that "perseverance is a habit regarding things to which we ought to stand, and those to which we ought not to stand, as well as those that are indifferent." Now a habit that directs us to do something well, or to omit something, is a virtue. Therefore perseverance is a virtue.
I answer that, According to the Philosopher (Ethic. ii, 3), "virtue is about the difficult and the good"; and so where there is a special kind of difficulty or goodness, there is a special virtue. Now a virtuous deed may involve goodness or difficulty on two counts. First, from the act's very species, which is considered in respect of the proper object of that act: secondly, from the length of time, since to persist long in something difficult involves a special difficulty. Hence to persist long in something good until it is accomplished belongs to a special virtue.
Accordingly just as temperance and fortitude are special virtues, for the reason that the one moderates pleasures of touch (which is of itself a difficult thing), while the other moderates fear and daring in connection with dangers of death (which also is something difficult in itself), so perseverance is a special virtue, since it consists in enduring delays in the above or other virtuous deeds, so far as necessity requires.
Reply to Objection 1: The Philosopher is taking perseverance there, as it is found in one who bears those things which are most difficult to endure long. Now it is difficult to endure, not good, but evil. And evils that involve danger of death, for the most part are not endured for a long time, because often they soon pass away: wherefore it is not on this account that perseverance has its chief title to praise. Among other evils foremost are those which are opposed to pleasures of touch, because evils of this kind affect the necessaries of life: such are the lack of food and the like, which at times call for long endurance. Now it is not difficult to endure these things for a long time for one who grieves not much at them, nor delights much in the contrary goods; as in the case of the temperate man, in whom these passions are not violent. But they are most difficult to bear for one who is strongly affected by such things, through lacking the perfect virtue that moderates these passions. Wherefore if perseverance be taken in this sense it is not a perfect virtue, but something imperfect in the genus of virtue. On the other hand, if we take perseverance as denoting long persistence in any kind of difficult good, it is consistent in one who has even perfect virtue: for even if it is less difficult for him to persist, yet he persists in the more perfect good. Wherefore such like perseverance may be a virtue, because virtue derives perfection from the aspect of good rather than from the aspect of difficulty.
Reply to Objection 2: Sometimes a virtue and its act go by the same name: thus Augustine says (Tract. in Joan. lxxix): "Faith is to believe without seeing." Yet it is possible to have a habit of virtue without performing the act: thus a poor man has the habit of magnificence without exercising the act. Sometimes, however, a person who has the habit, begins to perform the act, yet does not accomplish it, for instance a builder begins to build a house, but does not complete it. Accordingly we must reply that the term "perseverance" is sometimes used to denote the habit whereby one chooses to persevere, sometimes for the act of persevering: and sometimes one who has the habit of perseverance chooses to persevere and begins to carry out his choice by persisting for a time, yet completes not the act, through not persisting to the end. Now the end is twofold: one is the end of the work, the other is the end of human life. Properly speaking it belongs to perseverance to persevere to the end of the virtuous work, for instance that a soldier persevere to the end of the fight, and the magnificent man until his work be accomplished. There are, however, some virtues whose acts must endure throughout the whole of life, such as faith, hope, and charity, since they regard the last end of the entire life of man. Wherefore as regards these which are the principal virtues, the act of perseverance is not accomplished until the end of life. It is in this sense that Augustine speaks of perseverance as denoting the consummate act of perseverance.
Reply to Objection 3: Unchangeable persistence may belong to a virtue in two ways. First, on account of the intended end that is proper to that virtue; and thus to persist in good for a long time until the end, belongs to a special virtue called perseverance, which intends this as its special end. Secondly, by reason of the relation of the habit to its subject: and thus unchangeable persistence is consequent upon every virtue, inasmuch as virtue is a "quality difficult to change."
Objection 1: It seems that perseverance is not a part of fortitude. For, according to the Philosopher (Ethic. viii, 7), "perseverance is about pains of touch." But these belong to temperance. Therefore perseverance is a part of temperance rather than of fortitude.
Objection 2: Further, every part of a moral virtue is about certain passions which that virtue moderates. Now perseverance does not imply moderation of the passions: since the more violent the passions, the more praiseworthy is it to persevere in accordance with reason. Therefore it seems that perseverance is a part not of a moral virtue, but rather of prudence which perfects the reason.
Objection 3: Further, Augustine says (De Persev. i) that no one can lose perseverance; whereas one can lose the other virtues. Therefore perseverance is greater than all the other virtues. Now a principal virtue is greater than its part. Therefore perseverance is not a part of a virtue, but is itself a principal virtue.
On the contrary, Tully (De Invent. Rhet. ii) reckons perseverance as a part of fortitude.
I answer that, As stated above (Q[123], A[2]; FS, Q[61], AA[3],4), a principal virtue is one to which is principally ascribed something that lays claim to the praise of virtue, inasmuch as it practices it in connection with its own matter, wherein it is most difficult of accomplishment. In accordance with this it has been stated (Q[123], A[2]) that fortitude is a principal virtue, because it observes firmness in matters wherein it is most difficult to stand firm, namely in dangers of death. Wherefore it follows of necessity that every virtue which has a title to praise for the firm endurance of something difficult must be annexed to fortitude as secondary to principal virtue. Now the endurance of difficulty arising from delay in accomplishing a good work gives perseverance its claim to praise: nor is this so difficult as to endure dangers of death. Therefore perseverance is annexed to fortitude, as secondary to principal virtue.
Reply to Objection 1: The annexing of secondary to principal virtues depends not only on the matter [*Cf. Q[136], A[4], ad 2], but also on the mode, because in everything form is of more account than matter. Wherefore although, as to matter, perseverance seems to have more in common with temperance than with fortitude, yet, in mode, it has more in common with fortitude, in the point of standing firm against the difficulty arising from length of time.
Reply to Objection 2: The perseverance of which the Philosopher speaks (Ethic. vii, 4,7) does not moderate any passions, but consists merely in a certain firmness of reason and will. But perseverance, considered as a virtue, moderates certain passions, namely fear of weariness or failure on account of the delay. Hence this virtue, like fortitude, is in the irascible.
Reply to Objection 3: Augustine speaks there of perseverance, as denoting, not a virtuous habit, but a virtuous act sustained to the end, according to Mat. 24:13, "He that shall persevere to the end, he shall be saved." Hence it is incompatible with such like perseverance for it to be lost, since it would no longer endure to the end.
Objection 1: It seems that constancy does not pertain to perseverance. For constancy pertains to patience, as stated above (Q[137], A[5]): and patience differs from perseverance. Therefore constancy does not pertain to perseverance.
Objection 2: Further, "virtue is about the difficult and the good." Now it does not seem difficult to be constant in little works, but only in great deeds, which pertain to magnificence. Therefore constancy pertains to magnificence rather than to perseverance.
Objection 3: Further, if constancy pertained to perseverance, it would seem nowise to differ from it, since both denote a kind of unchangeableness. Yet they differ: for Macrobius (In Somn. Scip. i) condivides constancy with firmness by which he indicates perseverance, as stated above (Q[128] , A[6]). Therefore constancy does not pertain to perseverance.
On the contrary, One is said to be constant because one stands to a thing. Now it belongs to perseverance to stand to certain things, as appears from the definition given by Andronicus. Therefore constancy belongs to perseverance.
I answer that, Perseverance and constancy agree as to end, since it belongs to both to persist firmly in some good: but they differ as to those things which make it difficult to persist in good. Because the virtue of perseverance properly makes man persist firmly in good, against the difficulty that arises from the very continuance of the act: whereas constancy makes him persist firmly in good against difficulties arising from any other external hindrances. Hence perseverance takes precedence of constancy as a part of fortitude, because the difficulty arising from continuance of action is more intrinsic to the act of virtue than that which arises from external obstacles.
Reply to Objection 1: External obstacles to persistence in good are especially those which cause sorrow. Now patience is about sorrow, as stated above (Q[136], A[1]). Hence constancy agrees with perseverance as to end: while it agrees with patience as to those things which occasion difficulty. Now the end is of most account: wherefore constancy pertains to perseverance rather than to patience.
Reply to Objection 2: It is more difficult to persist in great deeds: yet in little or ordinary deeds, it is difficult to persist for any length of time, if not on account of the greatness of the deed which magnificence considers, yet from its very continuance which perseverance regards. Hence constancy may pertain to both.
Reply to Objection 3: Constancy pertains to perseverance in so far as it has something in common with it: but it is not the same thing in the point of their difference, as stated in the Article.
Objection 1: It seems that perseverance does not need the help of grace. For perseverance is a virtue, as stated above (A[1]). Now according to Tully (De Invent. Rhet. ii) virtue acts after the manner of nature. Therefore the sole inclination of virtue suffices for perseverance. Therefore this does not need the help of grace.
Objection 2: Further, the gift of Christ's grace is greater than the harm brought upon us by Adam, as appears from Rom. 5:15, seqq. Now "before sin man was so framed that he could persevere by means of what he had received," as Augustine says (De Correp. et Grat. xi). Much more therefore can man, after being repaired by the grace of Christ, persevere without the help of a further grace.
Objection 3: Further, sinful deeds are sometimes more difficult than deeds of virtue: hence it is said in the person of the wicked (Wis. 5:7): "We . . . have walked through hard ways." Now some persevere in sinful deeds without the help of another. Therefore man can also persevere in deeds of virtue without the help of grace.
On the contrary, Augustine says (De Persev. i): "We hold that perseverance is a gift of God, whereby we persevere unto the end, in Christ."
I answer that, As stated above (A[1], ad 2; A[2], ad 3), perseverance has a twofold signification. First, it denotes the habit of perseverance, considered as a virtue. In this way it needs the gift of habitual grace, even as the other infused virtues. Secondly, it may be taken to denote the act of perseverance enduring until death: and in this sense it needs not only habitual grace, but also the gratuitous help of God sustaining man in good until the end of life, as stated above (FS, Q[109], A[10]), when we were treating of grace. Because, since the free-will is changeable by its very nature, which changeableness is not taken away from it by the habitual grace bestowed in the present life, it is not in the power of the free-will, albeit repaired by grace, to abide unchangeably in good, though it is in its power to choose this: for it is often in our power to choose yet not to accomplish.
Reply to Objection 1: The virtue of perseverance, so far as it is concerned, inclines one to persevere: yet since it is a habit, and a habit is a thing one uses at will, it does not follow that a person who has the habit of virtue uses it unchangeably until death.
Reply to Objection 2: As Augustine says (De Correp. et Grat. xi), "it was given to the first man, not to persevere, but to be able to persevere of his free-will: because then no corruption was in human nature to make perseverance difficult. Now, however, by the grace of Christ, the predestined receive not only the possibility of persevering, but perseverance itself. Wherefore the first man whom no man threatened, of his own free-will rebelling against a threatening God, forfeited so great a happiness and so great a facility of avoiding sin: whereas these, although the world rage against their constancy, have persevered in faith."
Reply to Objection 3: Man is able by himself to fall into sin, but he cannot by himself arise from sin without the help of grace. Hence by falling into sin, so far as he is concerned man makes himself to be persevering in sin, unless he be delivered by God's grace. On the other hand, by doing good he does not make himself to be persevering in good, because he is able, by himself, to sin: wherefore he needs the help of grace for that end.