Chapter 18 — Part II: The Sacraments — The Holy Eucharist
Section 160. Finally, a most important reason was the necessity of opposing the heresy of those who denied that Christ, whole and entire, is contained under either species, and asserted that the body is contained under the species of bread without the blood, and the blood under the species of wine without the body. In order, therefore, to place more clearly before the eyes of all the truth of the Catholic faith, Communion under one kind, that is, under the species of bread, was most wisely introduced.