Baptism.

Obj. 3: Further, fruitfulness pertains to active generation. But a
man is regenerated spiritually by Baptism. Therefore fruitfulness is
not an effect of Baptism.

_On the contrary,_ Augustine says in the book on Infant Baptism (De
Pecc. Merit. et Remiss. i) that "the effect of Baptism is that the
baptized are incorporated in Christ." And Dionysius (Eccl. Hier. ii)
ascribes enlightenment to Baptism. And on Ps. 22:2, "He hath brought
me up on the water of refreshment," a gloss says that "the sinner's
soul, sterilized by drought, is made fruitful by Baptism."

_I answer that,_ By Baptism man is born again unto the spiritual
life, which is proper to the faithful of Christ, as the Apostle says
(Gal. 2:20): "And that I live now in the flesh; I live in the faith
of the Son of God." Now life is only in those members that are united
to the head, from which they derive sense and movement. And therefore
it follows of necessity that by Baptism man is incorporated in
Christ, as one of His members. Again, just as the members derive
sense and movement from the material head, so from their spiritual
Head, i.e. Christ, do His members derive spiritual sense consisting
in the knowledge of truth, and spiritual movement which results from
the instinct of grace. Hence it is written (John 1:14, 16): "We have
seen Him . . . full of grace and truth; and of His fulness we all
have received." And it follows from this that the baptized are
enlightened by Christ as to the knowledge of truth, and made fruitful
by Him with the fruitfulness of good works by the infusion of grace.

Reply Obj. 1: Adults who already believe in Christ are incorporated
in Him mentally. But afterwards, when they are baptized, they are
incorporated in Him, corporally, as it were, i.e. by the visible
sacrament; without the desire of which they could not have been
incorporated in Him even mentally.

Reply Obj. 2: The teacher enlightens outwardly and ministerially by
catechizing: but God enlightens the baptized inwardly, by preparing
their hearts for the reception of the doctrines of truth, according
to John 6:45: "It is written in the prophets . . . They shall all be
taught of God."

Reply Obj. 3: The fruitfulness which I ascribed as an effect of
Baptism is that by which man brings forth good works; not that by
which he begets others in Christ, as the Apostle says (1 Cor. 4:15):
"In Christ Jesus by the Gospel I have begotten you."
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