What is the Eucharist?
The ritual, sacramental action of thanksgiving to God which constitutes the principal Christian liturgical celebration of and communion in the paschal mystery of Christ. The liturgical action called the Eucharist is also traditionally known as the Holy Sacrifice of the Mass. The Holy Eucharist completes Christian initiation. The Sunday celebration of the Eucharist is at the heart of the Church's life.
Who can receive the Eucharist?
The Lord addresses an invitation to us, urging us to receive him in the sacrament of the Eucharist: "Truly, I say to you, unless you eat the flesh of the Son of man and drink his blood, you have no life in you." To respond to this invitation we must prepare ourselves for so great and so holy a moment. St. Paul urges us to examine our conscience: "Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup. For any one who eats and drinks without discerning the body eats and drinks judgment upon himself." Anyone conscious of a grave sin must receive the sacrament of Reconciliation before coming to communion. Before so great a sacrament, the faithful can only echo humbly and with ardent faith the words of the Centurion: "Domine, non sum dignus ut intres sub tectum meum, sed tantum dic verbo, et sanabitur anima mea" ("Lord, I am not worthy that you should enter under my roof, but only say the word and my soul will be healed.") To prepare for worthy reception of this sacrament, the faithful should observe the fast required in their Church. Bodily demeanor (gestures, clothing) ought to convey the respect, solemnity, and joy of this moment when Christ becomes our guest. It is in keeping with the very meaning of the Eucharist that the faithful, if they have the required dispositions, receive communion when they participate in the Mass. As the Second Vatican Council says: "That more perfect form of participation in the Mass whereby the faithful, after the priest's communion, receive the Lord's Body from the same sacrifice, is warmly recommended." The Church obliges the faithful to take part in the Divine Liturgy on Sundays and feast days and, prepared by the sacrament of Reconciliation, to receive the Eucharist at least once a year, if possible during the Easter season. But the Church strongly encourages the faithful to receive the holy Eucharist on Sundays and feast days, or more often still, even daily. Since Christ is sacramentally present under each of the species, communion under the species of bread alone makes it possible to receive all the fruit of Eucharistic grace. For pastoral reasons this manner of receiving communion has been legitimately established as the most common form in the Latin rite. But "the sign of communion is more complete when given under both kinds, since in that form the sign of the Eucharistic meal appears more clearly." This is the usual form of receiving communion in the Eastern rites.