“A man of exceptional ability, determination, and experience, whose intellectual stature shines out in his letters, Gregory made reform the keynote of his program. His exalted mystique of the papacy, set out in the twenty-seven propositions of his Dictatus (March 1075), included not only the pope’s personal sanctity inherited from St Peter, but his supremacy over, and right to depose, all princes, temporal as well as spiritual; all Christians were subject to the pope, who had supreme legislative and judicial power.”