Sacramentum Caritatis §37

The Eucharist and the risen Christ

37. Since the eucharistic liturgy is essentially an actio Dei which draws us into Christ through the Holy Spirit, its basic structure is not something within our power to change, nor can it be held hostage by the latest trends. Here too Saint Paul's irrefutable statement applies: "no one can lay any foundation other than the one that has been laid, which is Jesus Christ" (1 Cor 3:11). Again it is the Apostle of the Gentiles who assures us that, with regard to the Eucharist, he is presenting not his own teaching but what he himself has received (cf. 1 Cor 11:23). The celebration of the Eucharist implies and involves the living Tradition. The Church celebrates the eucharistic sacrifice in obedience to Christ's command, based on her experience of the Risen Lord and the outpouring of the Holy Spirit. For this reason, from the beginning, the Christian community has gathered for the fractio panis on the Lord's Day. Sunday, the day Christ rose from the dead, is also the first day of the week, the day which the Old Testament tradition saw as the beginning of God's work of creation. The day of creation has now become the day of the "new creation," the day of our liberation, when we commemorate Christ who died and rose again (113).

(113) Cf. Propositio 30. Weekday Masses, which the faithful are encouraged to attend, find their proper form on the day of the Lord, the day of Christ's resurrection; Propositio 43.