Catechism of the Catholic Church §608 — excerpt
After agreeing to baptize him along with the sinners, John the Baptist looked at Jesus and pointed him out as the "Lamb of God, who takes away the sin of the world".
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.