ves, as was stated above with
regard to prayer (Q. 83, A. 12), or to call others to witness, so
that one may refrain from breaking the vow, not only through fear of
God, but also through respect of men. Now a promise is the outcome
from a purpose of doing something: and a purpose presupposes
deliberation, since it is the act of a deliberate will. Accordingly
three things are essential to a vow: the first is deliberation; the
second is a purpose of the will; and the third is a promise, wherein
is completed the nature of a vow. Sometimes, however, two other
things are added as a sort of confirmation of the vow, namely,
pronouncement by word of mouth, according to Ps. 65:13, "I will pay
Thee my vows which my lips have uttered"; and the witnessing of
others. Hence the Master says (Sent. iv, D, 38) that a vow is "the
witnessing of a spontaneous promise and ought to be made to God and
about things relating to God": although the "witnessing" may strictly
refer to the inward protestation.

Reply Obj. 1: The conceiving of a good purpose is not confirmed by
the deliberation of the mind, unless the deliberation lead to a
promise.

Reply Obj. 2: Man's will moves the reason to promise something
relating to things subject to his will, and a vow takes its name from
the will forasmuch as it proceeds from the will as first mover.

Reply Obj. 3: He that puts his hand to the plough does something
already; while he that merely purposes to do something does nothing
so far. When, however, he promises, he already sets about doing,
although he does not yet fulfil his promise: even so, he that puts
his hand to the plough does not plough yet, nevertheless he stretches
out his hand for the purpose of ploughing.
_______________________

SECOND ARTICLE [II-II, Q. 88, Art. 2]

Whether a Vow Should Always Be About a Better Good?

Objection 1: It would seem that a vow need not be always about a
better good. A greater good is one that pertains to supererogation.
But vows are not only about matters of supererogation, but also about
matters of salvation: thus in Baptism men vow to renounce the devil
and his pomps, and to keep the faith, as a gloss observes on Ps.
75:12, "Vow ye, and pay to the Lord your God"; and Jacob vowed (Gen.
28:21) that the Lord should be his God. Now this above all is
necessary for salvation. Therefore vows are not only about a better
good.

Obj. 2: Further, Jephte is included among the saints (Heb. 11:32).
Yet he kille