Guillem Arnaud’s activity was untiring. During his exile in Carcassonne he occupied himself with the trial of the Seigneur de Niort, whom he sentenced in February or March, 1236.[25] In the early months of 1237 we hear of him in Querci, co-operating with Pierre Cella in harrying the heretics of Montauban. During his absence there occurred a crowning mercy in Toulouse, which threw the heretics into a spasm of terror and contributed greatly to their destruction. Raymond Gros, who had been a perfected heretic for more than twenty years, one of the most loved and trusted leaders of the sect, was suddenly converted. Tradition relates that a quarter of a century before he had been seized and consigned to the stake, when the prophetic spirit of St. Dominic, foreseeing that he would return to the Church and perform shining service in the cause of God, rescued him from the flames. On April 2, without heralding, he presented himself at the Dominican convent, humbly begged to be received into the Church, and promised to do whatever should be required of him. With the eagerness of an impassioned convert he proceeded to reveal all that lifelong intercourse with the Cathari had brought to his knowledge. So full were his recollections that several days were required to write down all the names and facts that crowded to his lips. The lists were long and embraced prominent nobles and citizens, confirming suspicion in many cases, and revealing heresy in other quarters where it was wholly unlooked for. Guillem Arnaud hurried back from Montauban to take full advantage of this act of Providence. The heretics were stunned. None of them dared to deny the truth of the accusations made by Raymond Gros. Many fled, some of whose names reappear in the massacre of Avignonet and the final catastrophe of Montségur. Many recanted and furnished further revelations. Long lists were made out of those who had been hereticated on their death-beds, and multitudes of corpses were exhumed and burned, with the resultant harvest of confiscations. It is difficult to exaggerate the severity of the blow thus received by heresy. Toulouse was its headquarters. Here were the nobles and knights, the consuls and rich burghers who had thus far defied scrutiny and had protected their less fortunate comrades. Now scattered and persecuted, forced to recant, or burned, the power of the secret organization was broken irrevocably. We can well appreciate the pious exultation of the chronicler as he winds up his account of the consternation and destruction thus visited upon the heretical community--“Their names are not written in the Book of Life, but their bodies here were burned and their souls are tortured in hell!” A single sentence of February 19, 1238, in which more than twenty penitents were consigned _en masse_ to perpetual imprisonment, shows the extent of the harvest and the haste of the harvesters.[26]