The Sacrament of the Holy Eucharist is a sacrament in which Christ becomes really present to us in a sacramental way under the appearance of bread and wine. Bread and wine are changed into the body and blood of Christ. Christ (food from heaven) gives himself to us. Time and eternity meet; humanity is touched by the divine.
It is a sacrifice in which Christ is offered as a sacrificial Victim to his Father. It is a re-presentation of the sacrifice of the cross. On the cross Christ offered himself in a bloody manner. On the altar Christ is contained in the sacred species and offers himself (for our reconciliation) in an unbloody manner.
It is the source and summit of the life of the Church. It contains Christ. All other sacraments, ministries, and apostolate work are oriented towards the Eucharist. The Eucharist keeps the Church in existence; is the sign and the cause of communion and life in the divine life; and the unity of the Church. It is the culmination of God’s action sanctifying the world in Christ and the worship people offer to Christ.
It is a mystery of faith.
Christ instituted the Eucharist as an expression (pledge) of his love for us. It is a precious gift of himself. He instituted it as a way to always be with us (so as to never depart from us); to keep alive the memory of his death and resurrection; to provide spiritual nourishment for the soul; and to provide a means to unite us.
Chapter six of the gospel of John reports the words of Jesus that prepare for the institution. It was instituted during a ritual meal (i.e., Last Supper with the Apostles). The ritual meal was a Passover meal. Jesus changes the ritual; he adds something – the Institution Narrative (see Luke 22:14-20). Apostles didn’t understand the meaning of the change. The event of Jesus’ death had not occurred. It wasn’t until after Jesus rose and with help from the Holy Spirit that they begin to understand the meaning.
Christ becomes “sacramentally” present [under a substantial (real) change to the bread and wine] by the actions and words of consecration of a priest. Bread and wine are given a new nature. We cannot perceive a change with the senses, but with a mind illumined by faith we believe it is possible with God, and we trust in the words of Christ. Bread and wine become spiritual food.
Christ (now sacramentally present) is offered [in sacrifice] by the ordained priest to the Father. The manner in which Christ is offered at Mass is different than the manner he offered himself to his Father on the cross. The victim is the same. On the cross Christ dies once; the sacrifice of the victim was brought about by the bloody death; and Christ offered himself and his suffering to his Father. On the altar Christ doesn’t die again; the sacrifice is shown by external signs (no blood is shed); the bread and wine is changed into the body and blood of Christ (transubstantiation) ; and Christ (under the eucharistic species of bread and wine) offers himself to his Father. The Mass is sometimes referred to as a sacrifice (the Sacrifice of the Mass). The one sacrifice is re-enacted and recalled in the Mass. Sometimes referred to as a non-bloody sacrifice.
The faithful participate in the offering of Christ (the Victim). The faithful unite their offerings (sufferings, prayers, works) and intercessions. Those members in already in heaven unite their offerings and intercessions. The Eucharistic sacrifice is offered for the departed awaiting heaven.
Christ continues to be present in the consecrated host after Mass. Since Christ would not be here in visible form, he desired to give us his sacramental presence. Christ remains present under signs that express and communicate his love. The body and blood of Christ cannot be apprehended by the senses, but only by faith.
Our response is to prepare ourselves by an examination of conscience, reception of sacrament of Reconciliation if conscious of grave sin, observance of the one hour fast required by the Church, and the conveyance of respect, solemnity, and joy for Christ with proper gestures and clothing. It is recommended that we receive communion each time we participate at Mass. Our obligation is to take part in the Mass on Sundays and holy days of obligation; and receive the Eucharist at least once a year, during the Easter season if possible.
The Eucharist unites us more intimately and closely to Christ. Christ dwells in us. The life grace is preserved, increased, and renewed. The bond of charity with Christ is strengthened. The Eucharist separates us from sin. It cleanses us from past venial sins and preserves us from future mortal sins. The Eucharist reinforces unity of the Church as the Mystical Body of Christ. The Eucharist is a sign of unity. Through reception of the Eucharist we are united to all the faithful in one body; our incorporation into the Church is renewed, strengthened, and deepened.