The Church believes that in the Eucharist bread and wine are changed into the body and blood of Jesus Christ. In reflecting on salvation history, the Church sees a foreshadowing of this outpouring of divine love in the offering of bread and wine by the priest Melchizedek (see Gen. 14:18). In addition, the unleavened bread of the Passover celebration commemorating the Exodus, God's gift of manna in the desert, and the cup of blessing of the Passover meal prefigure the Eucharist.
The Eucharistic language and actions are also present in two gospel miracle stories: the multiplication of the loaves and the transformation of water into wine at Cana. The superabundance of the miracle of the loaves points to the outpouring of grace in the Eucharist. And the festive wine points to the heavenly feast of the Father's kingdom.
Jesus declared the importance of eating his body and drinking his blood, a hard teaching that caused some disciples to leave him. This announcement was an invitation to believe in him as the source of eternal life, to believe that to receive the Eucharist is to receive the Lord himself.
The Lord established the sacrament of Eucharist at the Last Supper in the context of the Jewish feast of Passover. During this meal, he took unleavened bread, blessed and broke it, and gave it to his apostles, saying, "Take and eat. This is my Body, which will be broken for you. Do this in memory of me."
Similarly, Jesus took the third Passover cup of wine after the meal, a joyful sharing among friends, and proclaimed, "Take and drink. This is the Cup of my Blood, the Blood of the new and eternal covenant, which will be shed for you. Do this in memory of me."
Jesus instituted the Eucharist as a memorial of his death and resurrection, and he commanded his apostles to celebrate it until his return in glory. The Church has been faithful to his mandate from its first days, breaking bread on Sunday to commemorate Jesus' resurrection on Easter. The Church will never cease doing so until our Lord comes again in the fullness of time.