are full members of the Commission, though not as representatives of their church, and participated in the production of the paper, the aim of which was to seek common ground between the various traditions concerning the Christian rite of initiation (Baptism), the sacrament of the Eucharist, and the nature of holy orders, while also stating clearly the differences existing between them. The churches were invited to indicate their reactions to the contents of the document, with a view to "analyz(ing) the ecumenical implications for the churches at a future World Conference on Faith and Order." Relations with churches of the East The Catholic Church recognizes 21 Ecumenical or General Councils: Nicaea I (325), Constantinople I (381), Ephesus (431), Chalcedon (451), Constantinople II (553), Constantinople III (680–681), Nicaea II (787), Constantinople IV (869–870), Lateran I (1123), Lateran II (1139), Lateran III (1179), Lateran IV (1215), Lyons I (1245), Lyons II (1274), Vienne (1311–1312), Constance (1414–1418), Florence (1438–1445), Lateran V (1512–1517), Trent (1545–1563), Vatican I (1869–1870), Vatican II (1962–1965). Of these, the Eastern Orthodox Church of Byzantine tradition accepts only the first seven, the family of "non-Chalcedonian" or "pre-Chalcedonian" Churches only the first three, and the Assyrian Church of the East only the first two. In spite of this, dialogue has shown that even where divisions have lasted longer than previous communion – as with the schisms rooted in the Christological controversies at the Council of Ephesus (431) and the Council of Chalcedon (451) – the few doctrinal differences often but not always concern terminology, not substance. In fact, as little as a decade of dialogue has done more to heal the divisions than fifteen centuries of apologetics, stereotypes, and suspicion. Assyrian Church of the East The Catholic Church recognizes in the Assyrian Church of the East as one of the valid successor bodies of the ancient Church of the Mesopotamian valley, where Christianity had been established by around the year 150, though tradition traces apostolic origins with the Apostle Thomas and his disciples-successors Addai and Mari. The division between the Church of the Persian Empire and the Churches of Rome and Constantinople goes back to the disputes over the legitimacy of the terms mother of God and mother of Christ for the Virgin Mary, that came to a head at the Council of Ephesus in 431. The Assyrian Church had adopted radical Antiochene Christology, as articulated by Nestorius and Theodore of