ly. Therefore swearing is also.

Obj. 3: Further, swearing is directed to the purpose of confirming or
assuring. But it is a good thing for a man to confirm his assertion.
Therefore an oath is desirable as a good thing.

_On the contrary,_ It is written (Ecclus. 23:12): "A man that
sweareth much shall be filled with iniquity": and Augustine says (De
Mendacio xv) that "the Lord forbade swearing, in order that for your
own part you might not be fond of it, and take pleasure in seeking
occasions of swearing, as though it were a good thing."

_I answer that,_ Whatever is required merely as a remedy for an
infirmity or a defect, is not reckoned among those things that are
desirable for their own sake, but among those that are necessary:
this is clear in the case of medicine which is required as a remedy
for sickness. Now an oath is required as a remedy to a defect,
namely, some man's lack of belief in another man. Wherefore an oath
is not to be reckoned among those things that are desirable for their
own sake, but among those that are necessary for this life; and such
things are used unduly whenever they are used outside the bounds of
necessity. For this reason Augustine says (De Serm. Dom. in Monte i,
17): "He who understands that swearing is not to be held as a good
thing," i.e. desirable for its own sake, "restrains himself as far as
he can from uttering oaths, unless there be urgent need."

Reply Obj. 1: There is no parity between a vow and an oath: because
by a vow we direct something to the honor of God, so that for this
very reason a vow is an act of religion. On the other hand, in an
oath reverence for the name of God is taken in confirmation of a
promise. Hence what is confirmed by oath does not, for this reason,
become an act of religion, since moral acts take their species from
the end.

Reply Obj. 2: He who swears does indeed make use of his reverence or
love for the person by whom he swears: he does not, however, direct
his oath to the reverence or love of that person, but to something
else that is necessary for the present life.

Reply Obj. 3: Even as a medicine is useful for healing, and yet, the
stronger it is, the greater harm it does if it be taken unduly, so
too an oath is useful indeed as a means of confirmation, yet the
greater the reverence it demands the more dangerous it is, unless it
be employed aright; for, as it is written (Ecclus. 23:13), "if he
make it void," i.e. if he deceive his brother