Roman Catechism 18.20

Chapter 18 — Part II: The Sacraments — The Holy Eucharist

Section 20. The Eucharist Is But One Sacrament — But although there are two elements, as bread and wine, of which the entire Sacrament of the Eucharist is constituted, yet guided by the authority of the Church, we confess that this is not many Sacraments, but only one.