The Lord Jesus Christ, on the night he was handed over, took bread and after he had given thanks, broke it and said, “This is my body that is for you. Do this in remembrance of me.” The Church celebrates today the Solemnity of the Most Holy Body and Blood of Christ (Corpus Christi). It is a feast that celebrates in a special way the sacrament of the Eucharist as THE sacrament of the Church. It is a feast whose significance in the life of the Church cannot be emphasized enough, for although Christ continues to to be present in, and to the Church in many different ways, his presence in the Holy Eucharist is unique. In the species of bread and wine (which after the words of consecration are transformed into the body and blood of Christ), Christ remains present in, and to the Church in a very tangible way (referred to as real presence). In the sacrament of the Holy Eucharist, not only are the faithful able to 'touch' Christ as if he were physically present to them, but Christ also gives himself as food to them. The Holy Eucharist, in other words, is a sacrament through which the mystery of the great event of the Incarnation continues to be felt. 
The sacrament of the Holy Eucharist assumes such a central place in the life of the Church because it is at the heart of the greatest prayer that the Church offers (Mass). As a matter of fact, it can be said that the Holy Eucharist is the very heart of the Mass since it is around its table that the Church gathers for her greatest prayer. All the other components of the Mass point towards the table of the Holy Eucharist. Moreover, as St. Paul reminds us in today’s Second Reading, the Holy Eucharist is a sacrament that we celebrate in obedience to the command of Christ because it is tied to the redemptive work that he accomplished. The sacrament of the Holy Eucharist, then, is both a memorial of Jesus’ self-offering on behalf of his brothers and sisters as well as his invitation to them to join him in his self-offering (do this in memory of me). 
That Jesus Christ instituted the sacrament of the Holy Eucharist on the night of the Last Supper is not a mere coincidence. On that evening, Jesus had gathered together with the twelve apostles to celebrate perhaps the greatest feast in the Jewish religious calendar, the Passover. The Passover celebration was held to remember the great salvific event in the history of the community: the community’s liberation from slavery in Egypt. It was a feast that was mandated by God to be held on an annual basis to celebrate and recognize God’s continued presence to this community. When Jesus, therefore, instituted the sacrament of the Holy Eucharist on the eve of such a hallowed feast, he meant it to be his means of remaining present to both his disciples and to the community that would form around the disciples (the Church). 
Whereas the redemptive self-offering of Jesus Christ which was pre-figured in the events that took place in the upper room during the Last Supper did not in any way lessen the great event of the Passover, Jesus did see in them God making a new covenant with the world. Jesus body which was soon to be broken on the wood of the cross was the seal of a new covenant established between God and a new creation. Just like the Passover celebration, the Holy Eucharist becomes a memorial feast celebrating God creating a new community, albeit one that has been freed from condemnation. When members of the Christian community partake in a Eucharistic meal, they unite themselves to Christ and participate in the fullness of life that Christ has made possible for those who believe in him. 
As the sacrament of the body and blood of Christ, the Holy Eucharist also seeks to unite the members of the body of Christ one to another. One cannot be united to Christ and at the same time stay separated from the other members of Christ’s body. For not only has Christ incorporated the members of his body into himself in the incarnation, he continues to incorporate them to himself in the sacrament of the Holy Eucharist. Christ, the head, is never separated from the members of his body: “Whoever eats my flesh and drinks my blood lives in me and I live in that person” (cf. John 6:56). As such, when a member of the body of Christ seeks to become one with Christ, he/she ends up becoming one with the other members of Christ’s body. It is for this reason that the Holy Eucharist is referred to as the sacrament of unity.