Catechism of the Catholic Church §1355 — excerpt
In the communion, preceded by the Lord's prayer and the breaking of the bread, the faithful receive "the bread of heaven" and "the cup of salvation," the body and blood of Christ who offered himself "for the life 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.
Also cites: St. Justin, Apol. 1, 66,1-2: PG 6, 428