1. The board of presbyters, at least in the larger congregations, naturally and logically developed a head with a priority in rank. The office of president was universal in contemporary Jewish associations, and in Roman and Greek organisations. The creation of a chairman of the administrative body became a political necessity to expedite business, and to enforce discipline in the Christian societies. Moreover there was the example of the Apostles, who actually designated officers to continue their work (a) of teaching the true doctrines,[60:1] (b) of organising new churches, (c) of ordaining deacons and elders, and (d) in acting as head of the whole congregation.[60:2] Hence this change was natural, imperative, and easy; but the transition must have been gradual and must have lacked uniformity. 2. The president of the board of presbyters came, in course of time, to have a recognised supremacy in power as well as in rank, and the title of bishop was gradually restricted to his high office. After the death of the Apostles more duties devolved upon the president of the council, and it was in the course of things that the special word bishop, _i. e._, overseer or superintendent, should be applied to him. By the second century, at least, if not indeed before, the differentiation had begun and from that time on it can be plainly traced in the Church Fathers. Jerome states that at Alexandria until the middle of the third century the presbyters elected one of their number as president and called him bishop.[61:1] Hilarius says: "Every bishop is a presbyter, but not every presbyter a bishop; for he only is bishop who is the primate among the presbyters."[61:2] Examples, secular and ecclesiastical, were not lacking to warrant the change: (a) the Old Testament priesthood, (b) Christ and his Apostles, (c) the Apostles and their appointees, (d) the Emperor and his officials. The bishop soon professed to occupy the place of an Apostle instead of Christ as earlier, hence arose the idea of an "Apostolic seat" and "Apostolic succession."[61:3] He represented Christian unity of doctrine and discipline, and ruled over a recognised territory--first a single church, then a city, then a province. From the bishop it was only another step to the archbishop, the metropolitan, the patriarch, and the Pope.