CCC 1228 Hence Baptism is a bath of water in which the “imperishable seed” of the Word of God produces its life-giving effect.1 St. Augustine says of Baptism: “The word is brought to the material element, and it becomes a sacrament.”2

1 1 Pet 1:23; cf. Eph 5:26.
2 St. Augustine, In Jo. ev. 80, 3: PL 35, 1840.