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.'” 1322 Catechism of the Catholic Church.
The Holy Eucharist is a sacrament and a sacrifice. In the Holy Eucharist, under the appearances of bread and wine, the Lord Christ is contained, offered, and received. The whole Christ is really, truly, and substantially present in the Holy Eucharist. We use the words “really, truly, and substantially” to describe Christ’s presence in the Holy Eucharist in order to distinguish Our Lord’s teaching from that of mere men who falsely teach that the Holy Eucharist is only a sign or figure of Christ, or that He is present only by His power. All Christians, with but few minor exceptions, held the true doctrine of the Real Presence from the time of Christ until the Protestant Revolution in the sixteenth century. The word “Eucharist” means “Thanksgiving.”
But was Jesus eating his own body and blood when he had his ‘Last Supper’?” Sometimes amusing, but the answer is ‘yes’. St. Thomas Aquinas explains in the Summa Theologica (III, 81, 1):
“On the contrary, Jerome says (Ad Hedib., Ep. xxx), ‘The Lord Jesus Christ, Himself the guest and banquet, is both the partaker and what is eaten.’
Some have said that Christ during the supper gave His body and blood to His disciples, but did not partake of it Himself. But this seems improbable. Because Christ Himself was the first to fulfil what He required others to observe: hence He willed first to be baptized when imposing Baptism upon others: as we read in Acts 1:1: “Jesus began to do and to teach.” Hence He first of all took His own body and blood, and afterwards gave it to be taken by the disciples. Christ ate and drank at the supper, when He gave to the disciples the sacrament of His body and blood. Hence, ‘because the children partook ( ‘Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death…’ Hebrews 2:14) of His flesh and blood, He also hath been partaker in the same.
Another question is was the Eucharist the sacrificed body and blood even though when Jesus instituted it, he hadn’t yet been crucified?”
St. Thomas Aquinas explains in the Summa Theologica (III, 73, 5):
“This sacrament was instituted during the supper, so as in the future to be a memorial of our Lord’s Passion as accomplished. Hence He said expressively: ‘As often as ye shall do these things’, speaking of the future.” 1 Corinthians 11:26.
Now , how the real presence does not violate Christ’s physical incarnation by having his physical body be in multiple places at the summoning of the Priest in Masses all over the world? Christ is incarnated as a man in a physical body. A man’s physical body can only be at one place at a time.
St. Thomas explains in the Summa Theologica (III, 75, 1):
“Christ’s body is not in this sacrament in the same way as a body is in a place, which by its dimensions is commensurate with the place; but in a special manner which is proper to this sacrament. Hence we say that Christ’s body is upon many altars, not as in different places, but ‘sacramentally’: and thereby we do not understand that Christ is there only as in a sign, although a sacrament is a kind of sign; but that Christ’s body is here after a fashion proper to this sacrament, as stated above.”
Eucharist/Mass is not a resacrifice of Christ when it is called a sacrifice by Catechism of Catholic Church (1055, 1365) that is divine (1068), a re-presentation of the sacrifice of Christ (1366), is the same suffice of Christ (1367), is propitiatory (1367), and makes reparation of sins (1414).”
It is a “re-presentation” of Christ’s sacrifice, not a re-sacrificing of Christ. St. John of Damascus adds this: “God said, This is My body, and This is My blood, and this do ye in remembrance of Me. And so it is at His omnipotent command until He comes: for it was in this sense that He said until He comes: and the overshadowing power of the Holy Spirit becomes through the invocation the rain to this new tillage. For just as God made all that He made by the energy of the Holy Spirit, so also now the energy of the Spirit performs those things that are supernatural and which it is not possible to comprehend unless by faith alone” (An Exposition of the Orthodox Faith, IV:13). The sacrifice of Christ is once and for all time – the Mass/Eucharist is simply a continuation through time of the one timeless sacrifice of Christ upon the cross.
Like all the sacraments (CCC, no. 1123), the Eucharist is a sign which instructs us. It nourishes and strengthens our faith by what it signifies: the wisdom, love and power of God manifested to us by Christ in His Real Presence and in His Sacrifice. Eucharist fosters the virtue of faith insofar as it signifies the one faith of the Catholic Church. This faith is objectively grounded in the official proclamation of the Word of God in the Eucharistic liturgy, and celebrated in the Eucharistic Sacrifice offered by those in Holy Orders who, possessing apostolic succession, in communion with their bishop and the successor of Peter, legitimately exercise apostolic authority.
The Eucharist is also the source of hope. “Hope,” the Catechism of the Catholic Church reminds us, “is the theological virtue by which we desire the kingdom of heaven and eternal life as our happiness, placing our trust in Christ’s promises and relying not on our own strength, but on the help of the grace of the Holy Spirit” (no. 1817). The basis of this hope is the salvation won by the death and resurrection of Christ and the gift of His Holy Spirit poured out in our hearts (Romans 5:5-11; 8:23-25; Titus 3:6-7), which is sacramentally present in the Eucharist.
Finally, the Eucharist is the source of charity. As Pope John Paul II wrote: “Christian life is expressed in the fulfilling of the greatest commandment, that is to say, in the love of God and neighbor, and this love finds its source in the blessed Sacrament, which is commonly called the sacrament of love. The Eucharist signifies this charity, and therefore recalls it, makes it present and at the same time brings it about” (Dominicae Cenae, no. 5).
“Holy Communion is the shortest and the safest way to Heaven.” St. Pius X.
“If the angels could be jealous of men, they would be for one reason: Holy Communion.” St. Maximilian Kolbe.
“And now—there is much more. Instead of myself and my Christ and my love and my prayer, there is the might of a prayer stronger than thunder and milder than the flight of doves rising up from the Priest who is the Center of every priest, shaking the foundations of the universe and lifting up—me, Host, altar, sanctuary, people, church, abbey, forest, cities, continents, seas and worlds to God and plunging everything into Him.” Thomas Merton, The Sign of Jonas.