As Sohm has put it in his _Outlines of Church History_, “the city or _civitas_ was the lowest political unit of the Empire. It became the lowest political unit of the Church. In the constitution of the Church the territory of the city appeared as the episcopal diocese. In the constitution of the Empire the province, with the provincial governor, stood above the _civitas_. The episcopal dioceses were united in like manner under the direction of the metropolitan, the bishop of a provincial capital, forming an ecclesiastical province. In the constitution of the Empire, from the fourth century, several provinces composed an imperial diocese under an imperial governor (vicarius). The imperial diocese also (at least in certain parts of the Eastern Greek Church) formed, after the fourth century, part of the ecclesiastical constitution, as the district of a patriarch, to whom the metropolitans of the imperial dioceses were subordinate. Finally the general union of the churches corresponded to the general union of the Empire, with the imperial Council (the so-called Oecumenical Council) as its legitimate organ.... Thus in its old age the Roman Empire bequeathed its constitution to the young Church.... It was its last great legacy to the future.” And later Sohm goes on to say: “To this day the diocese of the Catholic bishop is the copy of the Roman _civitas_; the province of the Catholic archbishop, the copy of the Roman imperial province; and the Catholic Church under a Pope declared omnipotent by law, the copy of the ancient Roman Empire, with its Caesars who claimed the world as their possession.” The Church extended its limits in ancient times and still extends them by new conquests, just as the Empire did. The missionary expeditions of Gregory in the sixth century, like the Jesuit enterprises in North and South America in recent times, were carried out in the spirit of Caesar or Trajan, and, after the Christian conquest of England, Gregory spoke as a Roman Emperor might have spoken, when he said “In one faith He linked the boundaries of the East and the West.” The absolute power of the Emperor in the later period is continued in tradition by the infallibility of the Pope, and the remarks of the city prefect, Themistius, to Theodosius the Great, “thou art the living law,” might be made with propriety to the Pope of today. The title “Pontifex Maximus” is common to both rulers, and there is a striking similarity between other ecclesiastical titles and those in the official Roman list of the _Notitia Dignitatum_. Latin is the official language of the Church, as it was of the Empire; the Pope consults the College of Cardinals, as the Emperor consulted the Senate; Canon Law, which has been derived in part from Roman Civil law, is codified as Roman Law was; the Councils seem to follow the parliamentary procedure of the Roman Senate, and the dress of Church officials is reminiscent of Roman times. In other words, what is