Chapter 16 — Part II: The Sacraments — Baptism
Section 7. The word baptism, as is well known, is of Greek derivation. Although used in Sacred Scripture to express not only that ablution which forms part of the Sacrament, but also every species of ablution, and sometimes, figuratively, to express sufferings; yet it is employed by ecclesiastical writers to designate not every sort of bodily ablution, but that which forms part of the Sacrament and is administered with the prescribed form of words. In this sense the Apostles very frequently make use of the word in accordance with the institution of Christ the Lord.