Roman Catechism 18.95

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

Section 95. The Mystery of Transubstantiation — The next point to be explained is that the substance of the bread and wine does not continue to exist in the Sacrament after consecration. This truth, although well calculated to excite our profound admiration, is yet a necessary consequence from what has been already established.