Catechism of the Catholic Church
1341 The command of Jesus to repeat his actions and words "until he comes" does not only ask us to remember Jesus and what he did. It is directed at the liturgical celebration, by the apostles and their successors, of the memorial of Christ, of his life, of his death, of his Resurrection, and of his intercession in the presence of the Father. 167
1342 From the beginning the Church has been faithful to the Lord's command. Of the Church of Jerusalem it is written:
They devoted themselves to the apostles' teaching and fellowship, to the breaking of bread and the prayers.... Day by day, attending the temple together and breaking bread in their homes, they partook of food with glad and generous hearts. 168
1343 It was above all on "the first day of the week," Sunday, the day of Jesus' resurrection, that the Christians met "to break bread." 169 From that time on down to our own day the celebration of the Eucharist has been continued so that today we encounter it everywhere in the Church with the same fundamental structure. It remains the center of the Church's life.
1344 Thus from celebration to celebration, as they proclaim the Paschal mystery of Jesus "until he comes," the pilgrim People of God advances, "following the narrow way of the cross," 170 toward the heavenly banquet, when all the elect will be seated at the table of the kingdom.
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.