39. Furthermore, given the very nature of ecclesial communion and its relation to the sacrament of the Eucharist, it must be recalled that “the Eucharistic Sacrifice, while always offered in a particular community, is never a celebration of that community alone. In fact, the community, in receiving the Eucharistic presence of the Lord, receives the entire gift of salvation and shows, even in its lasting visible particular form, that it is the image and true presence of the one, holy, catholic and apostolic Church”.79 From this it follows that a truly Eucharistic community cannot be closed in upon itself, as though it were somehow self-sufficient; rather it must persevere in harmony with every other Catholic community.
40. The Eucharist creates communion and fosters communion. Saint Paul wrote to the faithful of Corinth explaining how their divisions, reflected in their Eucharistic gatherings, contradicted what they were celebrating, the Lord's Supper. The Apostle then urged them to reflect on the true reality of the Eucharist in order to return to the spirit of fraternal communion (cf. 1 Cor 11:17- 34). Saint Augustine effectively echoed this call when, in recalling the Apostle's words: “You are the body of Christ and individually members of it” (1 Cor 12: 27), he went on to say: “If you are his body and members of him, then you will find set on the Lord's table your own mystery. Yes, you receive your own mystery”.84 And from this observation he concludes: “Christ the Lord... hallowed at his table the mystery of our peace and unity. Whoever receives the mystery of unity without preserving the bonds of peace receives not a mystery for his benefit but evidence against himself”.85