emblem of universal sovereignty. Not imperial decrees, but papal bulls, must now rule the world. Who but the Bishop of Rome could wear this tiara? Who but he could be the representative of the new theocracy? He was the bishop of the metropolis whose empire never could pass away. But his city was in ruins. If his claim to precedency rested on the grandeur of his capital, he must yield to the Bishop of Constantinople. He must found a new claim, not on the greatness and antiquity of his capital, but on the superstitious veneration of the Christian world,--a claim which would be accepted. Now it happened that one of Leo's predecessors had instituted such a claim, which he would revive and enforce with new energy. Innocent had maintained, forty years before Leo, that the primacy of the Roman See was derived from Saint Peter,--that Christ had delegated to Peter supreme power as chief of the apostles; and that he, as the successor of Saint Peter, was entitled to his jurisdiction and privileges. This is the famous _jus divinum_ principle which constitutes the corner-stone of the papal fabric. On this claim was based the subsequent encroachments of the popes. Leo saw the force of this claim, and adopted it and intrenched himself behind it, and became forthwith more formidable than any of his predecessors or any living bishop; and he was sure that so long as the claim was allowed, no matter whether his city was great or small, his successors would become the spiritual dictators of Christendom. The dignity and power of the Roman bishop were now based on a new foundation. He was still venerable from the souvenirs of the Empire, but more potent as the successor of the chief of the apostles. Ambrose had successfully asserted the independent spiritual power of the bishops; Leo seized that sceptre and claimed it for the Bishop of Rome.