The baptism of John the Baptist

"IT was fitting for John to baptize, for four reasons: first, it was necessary for Christ to be baptized by John, in order that He might sanctify baptism; as Augustine observes, super Joan. (Tract. xiii in Joan.).

"Secondly, that Christ might be manifested. Whence John himself says (Jn 1:31): "That He," i.e. Christ, "may be made manifest in Israel, therefore am I come baptizing with water." For he announced Christ to the crowds that gathered around him; which was thus done much more easily than if he had gone in search of each individual, as Chrysostom observes, commenting on St. John (Hom. x in Mt.).

"Thirdly, that by his baptism he might accustom men to the baptism of Christ; wherefore Gregory says in a homily (Hom. vii in Evang.) that therefore did John baptize, "that, being consistent with his office of precursor, as he had preceded our Lord in birth, so he might also by baptizing precede Him who was about to baptize."

"Fourthly, that by persuading men to do penance, he might prepare men to receive worthily the baptism of Christ. Wherefore Bede [Cf. Scot. Erig. in Joan. iii, 24] says that "the baptism of John was as profitable before the baptism of Christ, as instruction in the faith profits the catechumens not yet baptized. For just as he preached penance, and foretold the baptism of Christ, and drew men to the knowledge of the Truth that hath appeared to the world, so do the ministers of the Church, after instructing men, chide them for their sins, and lastly promise them forgiveness in the baptism of Christ." "

~St. Thomas Aquinas: Summa Theologica, III, q. 38, a. 1.

The Preaching of Saint John the Baptist, by Bacchiacca.

Oil on wood, c. 1520; Szépmûvészeti Múzeum, Budapest.

Baptism of Christ

"AS Augustine says (Super Joan., Tract. xiii): "After being baptized, the Lord baptized, not with that baptism wherewith He was baptized." Wherefore, since He Himself baptized with His own baptism, it follows that He was not baptized with His own, but with John's baptism. And this was befitting: first, because John's baptism was peculiar in this, that he baptized, not in the Spirit, but only "in water"; while Christ did not need spiritual baptism, since He was filled with the grace of the Holy Ghost from the beginning of His conception, as we have made clear above (q. 34, a. 1). And this is the reason given by Chrysostom (Hom. de Bapt. Christi). Secondly, as Bede says on Mark 1:9, He was baptized with the baptism of John, that, "by being thus baptized, He might show His approval of John's baptism." Thirdly, as Gregory Nazianzen says (Orat. xxxix), "by going to John to be baptized by him, He sanctified baptism.""

~St. Thomas Aquinas: S.T.  III, q. 39, a. 2.

Baptism of Christ, by Bartolomé Esteban Murillo.
Oil on canvas,  c. 1655; Staatliche Museen, Berlin.