5 These words highlight both the sacrifice, which pertains to the essence of the Mass that is celebrated daily, and the sacrament in which those who participate in it through holy Communion eat the flesh of Christ and drink the blood of Christ, and thus receive grace, which is the beginning of eternal life, and the "medicine of immortality" according to Our Lord's words: "The man who eats my flesh and drinks my blood enjoys eternal life, and I will raise him up on the last day." (2)
Source: Mysterium Fidei (Vatican.va)