So far we have contemplated the Church of Christ as one in external communion, no less than by the inner bonds of charity and of sacramental life; but we now come to a period in which this external unity began to be to a certain extent dissolved, and that in great measure by the same outward influences which had at first secured its cohesion. [Sidenote: with the breaking up of the Roman Empire.] Heresies and schisms, especially the great heresy of Arius, had indeed troubled the Church and threatened to break the visible union existing between its branches in different countries; but it was not until after the dissolution of the Roman empire that the breach really came. Section I. _Jealousy between Rome and Constantinople._ [Sidenote: Reasons for Roman ascendancy.] During the flourishing days of the empire the city of Rome had naturally been looked up to with great reverence by all the other Churches of the world. Its political importance as the centre of government, the vast number {95} of its martyrs, its comparative freedom from heresy, and its connexion with the lives and deaths of St. Peter and St. Paul, all tended to give it a moral ascendancy which was gradually claimed as a right. This, however, did not take place without protests on the part of other Bishops, nor even without very definite disclaimers of any wish for or right to supreme authority on the part of the Bishops of Rome themselves. [Sidenote: Ambition of an Eastern Patriarch.] Constantinople, as being the new Rome and capital of the Eastern empire, was especially jealous of the claims of the mother city, and one of her Patriarchs, John the Faster, in the sixth century, first set the evil example of assuming the title of "Universal Bishop," a title which the Roman Pontiffs have since taken and retained. In proportion as the political division between East and West became more complete, so also did the tendency towards separation in ecclesiastical matters increase. [Sidenote: Beginnings of disunion.] Western dioceses, now peopled by the barbarian nations who had overrun Europe, still looked up to Rome as their centre and head; whilst the Eastern Bishops, under the sway of the decaying empire, clung to Constantinople. [Sidenote: Its crisis.] The controversy respecting the use of Images, and that about the Procession of the Holy Ghost from the Son as well as from the Father, were, however, the means of actually bringing about the cessation of all outward communion between East and West. Section 2. _The Iconoclast (or Image-breaking) Controversy._ [Sidenote: Dislike of images]