The attitude of the Roman Church to the imperial power at Henry the Third's death was externally respectful. The right of a German king to the crown of the city was undoubted, and the Pope was his lawful subject. Hitherto the initiative in reform had come from the civil magistrate. But the secret of the pontiff's strength lay in this: he, and he alone, could confer the crown, and had therefore the right of imposing conditions on its recipient. Frequent interregna had weakened the claim of the Transalpine monarch and prevented his power from taking firm root; his title was never by law hereditary: the holy Church had before sought and might again seek a defender elsewhere. And since the need of such defence had originated this transference of the Empire from the Greeks to the Franks, since to render it was the Emperor's chief function, it was surely the Pope's duty as well as his right to see that the candidate was capable of fulfilling his task, to degrade him if he rejected or misperformed it.
The first step was to remove a blemish in the constitution of the Church, by fixing a regular body to choose the supreme pontiff. This Nicholas II did in A.D. 1059, feebly reserving the rights of Henry IV and his successors. Then the reforming spirit, kindled by the abuses and depravity of the last century, advanced apace. It had two main objects: the enforcement of celibacy, especially on the secular clergy, who enjoyed in this respect considerable freedom, and the extinction of simony. In the former, the Emperors and a large part of the laity were not unwilling to join: the latter no one dared to defend in theory. But when Gregory VII declared that it was sin for the ecclesiastic to receive his benefice under conditions from a layman, and so condemned the whole system of feudal investitures to the clergy, he aimed a deadly blow at all secular authority. Half of the land and wealth of Germany was in the hands of bishops and abbots, who would now be freed from the monarch's control to pass under that of the Pope. In such a state of things government itself would be impossible.