The Lord, having loved those who were his own, loved them to the end. Knowing that the hour had come to leave this world and return to the Father, in the course of a meal He washed their feet and gave them the commandment of love.
By celebrating the Last Supper with His apostles in the course of the Passover meal, Jesus gave the Jewish Passover its definitive meaning. Jesus’ passing over to His Father by His death and Resurrection, the new Passover, is anticipated in the Supper and celebrated in the Eucharist, which fulfills the Jewish Passover and anticipates the final Passover of the Church in the glory of the kingdom. 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. At the heart of the Eucharistic celebration are the bread and wine that, by the words of Christ and the invocation of the Holy Spirit, become Christ’s Body and Blood.
It was above all on the first day of the week, Sunday, the day of Jesus’ Resurrection that the Christians met to break the bread. From that time on down to our own day of 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. (Catechism of the Catholic Church 1337, 1340 & 1341)