hesitation baptize them again in the name of the Blessed Trinity,
when they come in quest of the Catholic Faith." Didymus, too, says
(De Spir. Sanct.): "If indeed there be such a one with a mind so
foreign to faith as to baptize while omitting one of the aforesaid
names," viz. of the three Persons, "he baptizes invalidly."

_I answer that,_ As stated above (Q. 64, A. 3), the sacraments derive
their efficacy from Christ's institution. Consequently, if any of
those things be omitted which Christ instituted in regard to a
sacrament, it is invalid; save by special dispensation of Him Who did
not bind His power to the sacraments. Now Christ commanded the
sacrament of Baptism to be given with the invocation of the Trinity.
And consequently whatever is lacking to the full invocation of the
Trinity, destroys the integrity of Baptism.

Nor does it matter that in the name of one Person another is implied,
as the name of the Son is implied in that of the Father, or that he
who mentions the name of only one Person may believe aright in the
Three; because just as a sacrament requires sensible matter, so does
it require a sensible form. Hence, for the validity of the sacrament
it is not enough to imply or to believe in the Trinity, unless the
Trinity be expressed in sensible words. For this reason at Christ's
Baptism, wherein was the source of the sanctification of our Baptism,
the Trinity was present in sensible signs: viz. the Father in the
voice, the Son in the human nature, the Holy Ghost in the dove.

Reply Obj. 1: It was by a special revelation from Christ that in the
primitive Church the apostles baptized in the name of Christ; in
order that the name of Christ, which was hateful to Jews and
Gentiles, might become an object of veneration, in that the Holy
Ghost was given in Baptism at the invocation of that Name.

Reply Obj. 2: Ambrose here gives this reason why exception could,
without inconsistency, be allowed in the primitive Church; namely,
because the whole Trinity is implied in the name of Christ, and
therefore the form prescribed by Christ in the Gospel was observed in
its integrity, at least implicitly.

Reply Obj. 3: Pope Nicolas confirms his words by quoting the two
authorities given in the preceding objections: wherefore the answer
to this is clear from the two solutions given above.
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SEVENTH ARTICLE [III, Q. 66, Art. 7]

Whether Immersion in Water Is Necessary for Baptism?

Objectio