The character of the man seemed formed to achieve and to maintain this vast design; he was at once terrible and popular, courteous, generous, placable to his foes; yet there was a depth of cruelty in the heart of Frederick towards revolted subjects, which made him look on the atrocities of his allies, Eccelin di Romano, and the Salinguerras, but as legitimate means to quell insolent and stubborn rebellion.⁠ ⁠… “It is impossible to conceive a contrast more strong or more irreconcilable than the octogenarian Gregory, in his cloister palace, in his conclave of stern ascetics, with all but severe imprisonment within conventual walls, completely monastic in manners, habits, views, in corporate spirit, in celibacy, in rigid seclusion from the rest of mankind, in the conscientious determination to enslave, if possible, all Christendom to its inviolable unity of faith, and to the least possible latitude of discipline; and the gay and yet youthful Frederick, with his mingled assemblage of knights and ladies, of Christians, Jews, and Mohammedans, of poets and men of science, met, as it were, to enjoy and minister to enjoyment⁠—to cultivate the pure intellect⁠—where, if not the restraints of religion, at least the awful authority of churchmen was examined with freedom, sometimes ridiculed with sportive wit.”