hority of
Holy Writ would swear. But this is false. Therefore the antecedent is
false also.

Obj. 2: Further, one does not pay anything to a person by calling him
to witness. But he who swears by God pays something to Him for it is
written (Matt. 5:33): "Thou shall pay [Douay: 'perform'] thy oaths to
the Lord"; and Augustine says [*Serm. clxxx] that to swear (_jurare_)
is "to pay the right (_jus reddere_) of truth to God." Therefore to
swear is not to call God to witness.

Obj. 3: Further, the duties of a judge differ from the duties of a
witness, as shown above (QQ. 67, 70). Now sometimes a man, by
swearing, implores the Divine judgment, according to Ps. 7:5, "If I
have rendered to them that repaid me evils, let me deservedly fall
empty before my enemies." Therefore to swear is not to call God to
witness.

_On the contrary,_ Augustine says in a sermon on perjury (Serm.
clxxx): "When a man says: 'By God,' what else does he mean but that
God is his witness?"

_I answer that,_ As the Apostle says (Heb. 6:16), oaths are taken for
the purpose of confirmation. Now speculative propositions receive
confirmation from reason, which proceeds from principles known
naturally and infallibly true. But particular contingent facts
regarding man cannot be confirmed by a necessary reason, wherefore
propositions regarding such things are wont to be confirmed by
witnesses. Now a human witness does not suffice to confirm such
matters for two reasons. First, on account of man's lack of truth,
for many give way to lying, according to Ps. 16:10, "Their mouth hath
spoken lies [Vulg.: 'proudly']." Secondly, on account of [his] lack
of knowledge, since he can know neither the future, nor secret
thoughts, nor distant things: and yet men speak about such things,
and our everyday life requires that we should have some certitude
about them. Hence the need to have recourse to a Divine witness, for
neither can God lie, nor is anything hidden from Him. Now to call God
to witness is named _jurare_ (to swear) because it is established as
though it were a principle of law (_jure_) that what a man asserts
under the invocation of God as His witness should be accepted as
true. Now sometimes God is called to witness when we assert present
or past events, and this is termed a "declaratory oath"; while
sometimes God is called to witness in confirmation of something
future, and this is termed a "promissory oath." But oaths are not
employed in order to subs