According to the law of the Empire the emperor’s authority extended over the Church, its doctrine, its discipline, and its property. Such authority was exercised by the emperors from Constantine to Justinian. But the Church had always stood upon the principle that it was better to obey God rather than man. This had been maintained against the power of the pagan Empire, and was not to be sunned out of existence by imperial favour. It was still better to obey God rather than the emperor. The Church still should say who were its members and entitled to participate in the salvation which it mediated. Ecclesiastical authorities could excommunicate; that was their engine of coercion. These principles were incarnate in Ambrose, Bishop of Milan, withstanding and prohibiting Theodosius from Christian fellowship until he had done penance for the massacre at Thessalonica. Of necessity they inhered in the Church; they were of the essence of its strength to fulfil its purpose; they stood for the duly constituted power of Christian resolution to uphold and advance the peremptory truth of Christ. So such principles persisted through the time of the hostile and then the favouring Roman Empire. And when the Empire in fact crumbled and fell, what _de facto_ and _de jure_ authority was best fitted to take the place of the imperial supremacy? The Empire represented a universal secular dominion; the Church was also universal, and with a universality now reaching out beyond the Empire’s shrinking boundaries. In the midst of political fragments otherwise disjoined, the Church endured as the universal unity. The power of each Teutonic king was great in fact and law within his realm. Yet he was but a local potency, while the Church existed through his and other realms. And when the power of one Teutonic line (the Carolingian) reached something like universal sway, the Church was also there within and without. It held the learning of the time, and the culture which large-minded seculars respected; and quite as much as the empire of Charlemagne, it held the prestige of Rome. Witness the attitude of Charles Martel and Pippin toward Boniface the great apostle, and the attitude of Boniface toward the Gregories whose legate he proclaimed himself, and upon whose central authority he based his claims to be obeyed. Through the reforms of the Frankish Church, carried out by him with the support of Charles Martel and Pippin, the ecclesiastical supremacy of Rome was established. Charlemagne, indeed, from the nature and necessities of his own transcendent power, possessed in fact the ecclesiastical authority of the Roman emperors, whom men deemed his predecessors. But after him the secular power fell again into fragments scarcely locally efficient, while the Church’s universality of authority endured.