97 The Catholic Church, both in her praxis and in her solemn documents, holds that the communion of the particular Churches with the Church of Rome, and of their Bishops with the Bishop of Rome, is—in God's plan—an essential requisite of full and visible communion. Indeed full communion, of which the Eucharist is the highest sacramental manifestation, needs to be visibly expressed in a ministry in which all the Bishops recognize that they are united in Christ and all the faithful find confirmation for their faith. The first part of the Acts of the Apostles presents Peter as the one who speaks in the name of the apostolic group and who serves the unity of the community—all the while respecting the authority of James, the head of the Church in Jerusalem. This function of Peter must continue in the Church so that under her sole Head, who is Jesus Christ, she may be visibly present in the world as the communion of all his disciples. Do not many of those involved in ecumenism today feel a need for such a ministry? A ministry which presides in truth and love so that the ship—that beautiful symbol which the World Council of Churches has chosen as its emblem— will not be buffeted by the storms and will one day reach its haven.
Source: Ut Unum Sint (Vatican.va)