Regarded from this point of view, the history of the Papacy may be compressed within limits which rather accentuate than obscure its interest, and, at the same time, a very ample account may be given of some of its more instructive phases. The first phase, before the Bishop of Rome became a Pope, in the distinctive sense of the word, is best illustrated by taking the bishopric of Callistus at the beginning of the third century. The Roman bishopric was then one of several "apostolic Sees," rarely claiming authority over other bishoprics, and still more rarely finding such a claim acknowledged: thrown somewhat into the shade by the vastly greater strength of the Eastern churches, yet having an immense and as yet undeveloped resource in the tradition, which was now generally accepted, that it had been founded by the two princes of the apostles. There was, however, in three hundred years, no Roman bishop sufficiently endowed to develop this resource, and the fourth century still found the Roman See so little elevated that its African neighbours disdainfully rejected its claim of authority. Then the far-reaching change which followed the conversion of Constantine bestowed on it a material splendour and a secular authority which gave it a distinctive place in Christendom, and a study of the life of Bishop Damasus shows us the extension of its prestige and the exploitation of its tradition; while the founding of a rival imperial city in the East and the obliteration of all other apostolic Sees withdrew half of Christendom from Roman influence before its ecumenic claim was fully developed.