Reply Obj. 2: He who promises something gives it already in as far as he binds himself to give it: even as a thing is said to be made when its cause is made, because the effect is contained virtually in its cause. This is why we thank not only a giver, but also one who promises to give.
Reply Obj. 3: A vow is made to God alone, whereas a promise may be made to a man also: and this very promise of good, which is made to a man, may be the matter of a vow, and in so far as it is a virtuous act. This is how we are to understand vows whereby we vow something to the saints or to one's superiors: so that the promise made to the saints or to one's superiors is the matter of the vow, in so far as one vows to God to fulfil what one has promised to the saints or one's superiors. _______________________
SIXTH ARTICLE [II-II, Q. 88, Art. 6]
Whether It Is More Praiseworthy and Meritorious to Do Something in
Fulfilment of a Vow, Than Without a Vow?
Objection 1: It would seem that it is more praiseworthy and meritorious to do a thing without a vow than in fulfilment of a vow. Prosper says (De Vita Contempl. ii): "We should abstain or fast without putting ourselves under the necessity of fasting, lest that which we are free to do be done without devotion and unwillingly." Now he who vows to fast puts himself under the necessity of fasting. Therefore it would be better for him to fast without taking the vow.
Obj. 2: Further, the Apostle says (2 Cor. 9:7): "Everyone as he hath determined in his heart, not with sadness, or of necessity: for God loveth a cheerful giver." Now some fulfil sorrowfully what they have vowed: and this seems to be due to the necessity arising from the vow, for necessity is a cause of sorrow according to Metaph. v [*Ed. Did. iv, 5]. Therefore, it is better to do something without a vow, than in fulfilment of a vow.
Obj. 3: Further, a vow is necessary for the purpose of fixing the will on that which is vowed, as stated above (A. 4). But the will cannot be more fixed on a thing than when it actually does that thing. Therefore it is no better to do a thing in fulfilment of a vow than without a vow.
On the contrary, A gloss on the words of Ps. 75:12, "Vow ye and pay," says: "Vows are counseled to the will." But a counsel is about none but a better good. Therefore it is better to do a deed in fulfilment of a vow than without a vow: since he that does it without a vow fulfils only one counsel, viz. the counsel to do it, whereas he that does it with a vow, fulfils two counsels, viz. the counsel to vow and the counsel to do it.
I answer that, For three reasons it is better and more meritorious to do one and the same deed with a vow than without. First, because to vow, as stated above (A. 5) is an act of religion which is the chief of the moral virtues. Now the more excellent the virtue the better and more meritorious the deed. Wherefore the act of an inferior virtue is the better and more meritorious for being commanded by a superior virtue, whose act it becomes through being commanded by it, just as the act of faith or hope is better if it be commanded by charity. Hence the works of the other moral virtues (for instance, fasting, which is an act of abstinence; and being continent, which is an act of chastity) are better and more meritorious, if they be done in fulfilment of a vow, since thus they belong to the divine worship, being like sacrifices to God. Wherefore Augustine says (De Virg. viii) that "not even is virginity honorable as such, but only when it is consecrated to God, and cherished by godly continence."
Secondly, because he that vows something and does it, subjects himself to God more than he that only does it; for he subjects himself to God not only as to the act, but also as to the power, since in future he cannot do something else. Even so he gives more who gives the tree with its fruit, than he that gives the fruit only, as Anselm [*Eadmer] observes (De Simil. viii). For this reason, we thank even those who promise, as stated above (A. 5, ad 2).