10 In connection with this matter it is of importance to consider that in the Eucharist, seeing that it was instituted by Christ as "a perpetual memorial of His Passion" ( Opusc . lvii. Offic. de festo Corporis Christi ), is proclaimed to the Christian the necessity of a salutary self-chastisement. For Jesus said to those first priests of His: "Do this in memory of Me" (Luke xxii, 18); that is to say, do this for the commemoration of My pains, My sorrows, My grievous afflictions, My death upon the Cross. Wherefore this Sacrament is at the same time a Sacrifice, seasonable throughout the entire period of our penance; and it is likewise a standing exhortation to all manner of toil, and a solemn and severe rebuke to those carnal pleasures which some are not ashamed so highly to praise and extol: "As often as ye shall eat this bread, and drink this chalice, ye shall announce the death of the Lord, until He come" (1 Cor. xi., 26).
Source: Mirae Caritatis (Vatican.va)