In connection with this work Irenæus made a collection of books for use in the church. His collection comprised the following: Matthew, Mark, Luke, John, Acts, Romans, First Corinthians, Second Corinthians, Galatians, Ephesians, Philippians, Colossians, First Thessalonians, Second Thessalonians, First Timothy, Second Timothy, Titus, Philemon, First John, and Revelation--twenty books in all. In the work of establishing the Roman Catholic church and the New Testament canon Irenæus was succeeded, early in the third century, by Tertullian and Clement of Alexandria. They adopted the list of books made by him. The books adopted by these Fathers were selected from a large number of Christian writings then extant--forty or more gospels, nearly as many Acts of Apostles, a score of Revelations, and a hundred epistles. Each church had one or more books which were used in that church. No divine authority, however, was ascribed to any of them. Why did the Fathers choose these particular books? Above all, why did they choose four gospels instead of one? We never see four biographies of Washington, of Cromwell, or of Napoleon, bound in one volume; yet here we have four different biographies of Jesus in one book. Irenæus says it is because "there are four quarters of the earth in which we live, and four universal winds." Instead of this artificial reason he could have given a natural, a rational, and a truthful reason. While primitive Christians, as we have seen, were divided into many sects, the principal sects may be grouped into three divisions: 1. The Petrine churches, comprising the church of Rome and other churches which recognized Peter as the chief of the apostles and the visible head of the church on earth; 2. The Pauline sects, which accepted Paul as the true exponent of Christianity; 3. The Johannine or Eastern churches, which regarded John as their founder. A collection of books to be acceptable to all of these churches must contain the favorite books of each. The First Gospel, written about the time this church union movement was inaugurated, was adopted by the Petrine churches. The Second Gospel was also highly valued by the church of Rome. The Third Gospel, a revised and enlarged edition of the Pauline Gospel of Marcion, had become the standard authority of Pauline Christians. The Fourth Gospel, which had superseded other and older gospels, was generally read in the Johannine churches. The Acts of the Apostles, written for the purpose of healing the dissensions that had arisen between the followers of Peter and Paul, was acceptable to both Petrines and Paulines. The Epistles of Paul were of course received by the Pauline churches, while the First Epistle of John was generally received by the Eastern churches. The collection would not be complete without a Revelation, and the Revelation of John was selected.