The Roman Church inherited, together with the city, the tradition of Roman dominion over the world. Ancient Rome largely shaped modern Christianity,--by the transmission of the idea of the authority which the Empire once exerted to the Church which grew up upon its ruins. The tremendous drama of Roman history displayed itself to the imagination from scene to scene, from act to act, with completeness of poetic progress and climax,--first the growth, the extension, the absoluteness of material supremacy, the heathen being made the instruments of Divine power for preparing the world for the revelation of the true God; then the tragedy of Christ's death wrought by Roman hands, and the expiation of it in the fall of the Roman imperial power; followed by the new era in which Rome again was asserting herself as mistress of the world, but now with spiritual instead of material supremacy, and with a dominion against which the gates of hell itself should not prevail.
It was, indeed, not at once that this conception of the Church as the inheritor of the rights of Rome to the obedience of mankind took form. It grew slowly and against opposition. But at the end of the eleventh century, through the genius of Pope Gregory VII., the ideas hitherto disputed, of the supreme authority of the Pope within the Church and of the supremacy of the Church over the State, were established as the accepted ecclesiastical theory, and adopted as the basis of the definitely organized ecclesiastical system. Little more than a hundred years later, at the beginning of the thirteenth century, Innocent III. enforced the claims of the Church with a vigor and ability hardly less than that of his great predecessor, maintaining openly that the Pope--Pontifex Maximus--was the vicar of God upon earth.
This theory was the logical conclusion from a long series of historic premises; and resting upon a firm foundation of dogma, it was supported by the genuine belief, no less than by the worldly interests and ambitions, of those who profited by it. The ideal it presented was at once a simple and a noble conception,--narrow indeed, for the ignorance of men was such that only narrow conceptions, in matters relating to the nature and destiny of man and the order of the universe, were possible. But it was a theory that offered an apparently sufficient solution of the mysteries of religion, of the relation between God and man, between the visible creation and the unseen world. It was a theory of a material rather than a spiritual order: it reduced the things of the spirit into terms of the things of the flesh. It was crude, it was easily comprehensible, it was fitted to the mental conditions of the age.