I swear it’s okay to sometime swear.
1 It has seemed foolish to some people to bind oneself by a vow to obey anyone, or to any kind of practice. In fact, the more freely any good action is done, the more virtuous it seems to be. On the other hand, the more and the greater the necessity whereby a man is constrained to a certain practice, the less freely does it seem to be performed. So, it appears derogatory to the praiseworthy character of virtuous acts for them to be done under the necessity of obedience or a vow.
2 Now, these men seem to ignore the meaning of necessity. In fact, there are two kinds of necessity. One is that of coaction. This kind decreases the value of virtuous acts, because it is contrary to the voluntary, for what is done under coaction is what is against the will.
But there is another necessity that results from interior inclination. This does not diminish the value of a virtuous act, but increases it, for it makes the will incline more intensely toward an act of virtue. Indeed, it is evident that the more perfect a habit of virtue is, the more forcefully does it make the will tend to the good of virtue, and less likely to fall short of it. So that, if it reaches the end of perfection, it confers a certain necessity of acting well, as in the case of the blessed who are not able to sin, as will appear later. Yet, because of this, neither is any freedom of will lost, nor goodness of the act.
3 However, there is still another necessity resulting from the end, as when we say that someone must have a ship in order to cross the sea. Again it is evident that this necessity does not decrease freedom of will or the goodness of the acts. Rather, the fact that a man does something that is necessary for an end is praiseworthy in itself; and the better the end, the more praiseworthy it is.
4 Now, it is clear that the necessity of practicing what one has vowed to do, or of obeying a person to whom one has subjected himself, is not the necessity of coaction or even that resulting from interior inclination, but it is from a relation to the end. For it is necessary for a person who takes a vow to do this or that thing if he is to fulfill the vow or practice obedience. So, since these ends are praiseworthy, inasmuch as by them man subjects himself to God, the aforesaid necessity in no way diminishes the value of virtue.
5 We should further consider that the carrying out of things which a person has vowed, or the fulfilling of the orders of a man to whom the person has subjected himself for God’s sake, are actions worthy of greater praise and reward.
It is possible, of course, for one act to pertain to two vices, provided the act of one vice be directed to the end of another vice. For instance, when a man steals so that he may fornicate, the act is specifically one of avarice, but by its intention it belongs to lust. In the same way, it also happens in the case of virtues that the act of one virtue is ordered to another virtue. Thus, when one gives away his possessions so that he may enjoy the friendship of charity with another man, this act specifically belongs to liberality, but from its end it pertains to charity. Now, acts of this kind acquire greater value from the greater virtue, that is, from charity rather than from liberality. Hence, though it loses its character as an exclusive act of liberality by virtue of its ordination to charity, it will be more praiseworthy and worthy of greater reward than if it were done liberally, with no relation to charity.
6 So, let us suppose a man performing some work of a definite virtue, say a man who is fasting or restraining himself continently from sexual pleasure—now, if he does this without a vow it will be an act of chastity or of abstinence, but if he does it as a result of a vow it is referred further to another virtue whose scope includes the vowing of something to God; that is, to the virtue of religion which is better than chastity or abstinence, inasmuch as it makes us rightly disposed in relation to God. So, the act of abstinence or continence will be more praiseworthy in the case of the man who performs it under a vow, even though he does not take so much delight in abstinence or continence due to the fact that he is taking his delight in a higher virtue, that is, religion.
7 Again, what is most important in virtue is a proper end, for the rational character of a good act stems chiefly from the end. So, if the end is more eminent, then, even if one is somewhat less than perfect in the act, it will be for him a more virtuous act. For example, take the case of a man who proposes to make a long journey for a virtuous purpose, while another man undertakes a short one; he who proposes to do more for the sake of virtue will be more praiseworthy, even though he makes slower progress on the trip.
But suppose a man does something for God’s sake, offering this act to God: if he does this under a vow he offers God not only the act, but also his power. Thus, it is evident that his intention is to offer something greater to God. So, his act will be more virtuous by reason of his intention for a greater good, even if, in the execution of it, another man might appear more fervent.
8 Besides, the act of will which precedes an act continues in its power through the whole performance of the act, and renders it worthy of praise, even when the agent is not thinking during the execution of the work of the commitment of will from which the act began. In fact, it is not necessary for a man who undertakes a journey for God’s sake actually to think about God during every part of the trip.
Now, it is clear that the man who vows that he will do a certain thing wills it more intensely than one who simply decides to do it, for the first man not only wills to do it, but he wills to strengthen himself so that he will not fail to act. So, by this act of voluntary intention there is produced a praiseworthy execution of the vow accompanied by a certain fervor, even when the will-act is not actually continued during the operation, or is continued in a slack way.
Notes This can be vouched for out of common experience.
9 And so, what is done as a result of a vow becomes more praiseworthy than what is done without a vow, provided other conditions are equal.