Summary: After the Second Vatican Council the life of the Catholic Church teneded to be based on the principle of "communion" which is realized in various environments in specifric ways in the relationship between the universal Church and local churches. This relationship is presented in the documents of the Church (1) As "Communion of Churches" and (2) as "The body of the Church" which receives its creative force above all from the Eucharist. The Great Jubilee of the year 2000, to renew this communion in the life of the Church has chosen (3) The Eucharist, especially as memorial (anamnesis), which in its life reveals: communion, solidarity and the trinitarian love of God towards humankind, which reach their fullest expression in real life. In this way there is created a renewed awareness of the Church and a deepened sense of the relationship between the universal and local churches based on the principle of reciprocal understanding and of reciprocal internal enrichment. By these means the universal Church, guided by the successors of Peter, wishes to gather together all people in the local Churches, and enter into the new millennium as a unique reality of the people of God.