Chapter 16 — Part II: The Sacraments — Baptism
Section 13. It is all the more necessary to impress this on the minds of the faithful lest they fall into the common error of thinking that the baptismal water, preserved in the sacred font, constitutes the Sacrament. The Sacrament of Baptism can be said to exist only when we actually apply the water to someone by way of ablution, while using the words appointed by our Lord.