The Holy Eucharist completes Christian initiation. Those who have been raised to the dignity of the royal priesthood by Baptism and configured more deeply to Christ by Confirmation participate with the whole community in the Lord's own sacrifice by means of the Eucharist.
“At the Last Supper, on the night he was betrayed, our Savior instituted the Eucharistic sacrifice of his Body and Blood. This he did in order to perpetuate the sacrifice of the cross throughout the ages until he should come again, and so to entrust to his beloved Spouse, the Church, a memorial of his death and resurrection: a sacrament of love, a sign of unity, a bond of charity, a Paschal banquet ‘in which Christ is consumed, the mind is filled with grace, and a pledge of future glory is given to us.’” (Catechism of the Catholic Church, 1322–1333)
The greatest of all the sacraments, the Holy Eucharist is the living presence of Christ in our Holy Church. The celebration of the Holy Eucharist at Holy Mass is truly the source and summit of our Christian life. It is the source of our Christian life because from the Holy Eucharist all graces that aid the Christian life flow. It is the summit because all the graces that are given through the Holy Eucharist lead those who received the graces back to the Holy Eucharist. When we truly understand that the Eucharist is Christ himself and not a mere symbol, it all makes sense: the beginning and end of our lives as Christians is Christ and Christ alone.