In fact the zealot, however loving and charitable he might otherwise be, was taught and believed that compassion for the sufferings of the heretic was not only a weakness but a sin. As well might he sympathize with Satan and his demons writhing in the endless torment of hell. If a just and omnipotent God wreaked divine vengeance on those of his creatures who offended him, it was not for man to question the righteousness of his ways, but humbly to imitate his example and rejoice when the opportunity to do so was vouchsafed to him. The stern moralists of the age held it to be a Christian duty to find pleasure in contemplating the anguish of the sinner. Gregory the Great, five centuries before, had argued that the bliss of the elect in heaven would not be perfect unless they were able to look across the abyss and enjoy the agonies of their brethren in eternal fire. This idea was a popular one and was not allowed to grow obsolete. Peter Lombard, the great "Master of Sentences," whose "Sentences," produced about the middle of the twelfth century, was the leading authority in the schools, quotes St. Gregory with approbation, and enlarges upon the satisfaction which the just will feel in the ineffable misery of the damned. Even the mystic tenderness of Bonaventura does not prevent him from echoing the same terrible exultation. When such were the sentiments in which all thinking men were trained, and such were the views which they disseminated among the people, it is not to be supposed that any feelings of compassion for the sufferers would deter the most charitable from the rigid exercise of justice. The ruthless extermination of heresy was a work which could only be pleasing to the righteous, whether simply as spectators or whether they were called by conscience or by station to the higher duties of active persecution. If, notwithstanding this, any scruple remained, the schoolmen easily removed it by proving that persecution was a work of charity, for the benefit of the persecuted.[212]