Christus totus in capite et in corpore
36. The "subject" of the liturgy's intrinsic beauty is Christ himself, risen and glorified in the Holy Spirit, who includes the Church in his work. (109) Here we can recall an evocative phrase of Saint Augustine which strikingly describes this dynamic of faith proper to the Eucharist. The great Bishop of Hippo, speaking specifically of the eucharistic mystery, stresses the fact that Christ assimilates us to himself: "The bread you see on the altar, sanctified by the word of God, is the body of Christ. The chalice, or rather, what the chalice contains, sanctified by the word of God, is the blood of Christ. In these signs, Christ the Lord willed to entrust to us his body and the blood which he shed for the forgiveness of our sins. If you have received them properly, you yourselves are what you have received." (110) Consequently, "not only have we become Christians, we have become Christ himself." (111) We can thus contemplate God's mysterious work, which brings about a profound unity between ourselves and the Lord Jesus: "one should not believe that Christ is in the head but not in the body; rather he is complete in the head and in the body." (112)
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).