Chapter 18 — Part II: The Sacraments — The Holy Eucharist
Section 60. The words mystery of faith, which are subjoined, do not exclude the reality, but signify that what lies hidden and concealed and far removed from the perception of the eye, is to be believed with firm faith. In this passage, however, these words bear a meaning different from that which they have when applied also to Baptism. Here the mystery of faith consists in seeing by faith the blood of Christ veiled under the species of wine; but Baptism is justly called by us the Sacrament of faith, by the Greeks, the mystery of faith, because it embraces the entire profession of the Christian faith.