“Christ took the bread and the chalice, gave thanks, broke the bread and gave it to his disciples, saying: Take, eat and drink: this is my Body; this is the chalice of my Blood. Do this in memory of me.” Hence, the Church has arranged the entire celebration of the Liturgy of the Eucharist in parts corresponding to precisely these words and actions of  Christ, namely:
At the Preparation of the Gifts, bread and wine with water are brought to the altar, the same elements, that is to say, which Christ took into his hands.
In the Eucharistic Prayer, thanks is given to God for the whole work of salvation, and the offerings become the Body and Blood of Christ.
Through the fraction and through Communion, the faithful, though many, receive from the one bread the Lord’s Body and from the one chalice the Lord’s Blood in the same way that the Apostles received them from the hands of Christ himself.”