It is not clear whether Abelard stopped teaching after 1136, or whether he continued with all except his lectures on logic until as late as 1141. Whatever the exact timing, a process was instigated by William of St-Thierry, who discovered what he considered to be heresies in some of Abelard's teaching. In spring 1140 he wrote to the Bishop of Chartres and to Bernard of Clairvaux, denouncing them. Another, less distinguished, theologian, Thomas of Morigny, also produced at the same time a list of Abelard's supposed heresies, perhaps at Bernard's instigation. Bernard's complaint mainly was that Abelard had applied logic where it is not applicable, and that is illogical.[39]
Amid pressure from Bernard, Abelard challenged Bernard either to withdraw his accusations, or to make them publicly at the important church council at Sens planned for 2 June 1141. In so doing, Abelard put himself into the position of the wronged party and forced Bernard to defend himself from the accusation of slander. Bernard avoided this trap, however: on the eve of the council, he called a private meeting of the assembled bishops and persuaded them to condemn, one by one, each of the heretical propositions he attributed to Abelard. When Abelard appeared at the council the next day, he was presented with a list of condemned propositions imputed to him.[40]
Unable to answer to these propositions, Abelard left the assembly, appealed to the Pope, and set off for Rome, hoping that the Pope would be more supportive. However, this hope was unfounded. On 16 July 1141, Pope Innocent II issued a bull excommunicating Abelard and his followers and imposing perpetual silence on him, and in a second document, he ordered Abelard to be confined in a monastery and his books to be burned. Abelard was saved from this sentence, however, by Peter the Venerable, abbot of Cluny. Abelard had stopped there, on his way to Rome, before the papal condemnation had reached France. Peter persuaded Abelard, already old, to give up his journey and stay at the monastery. Peter managed to arrange a reconciliation with Bernard, to have the sentence of excommunication lifted, and to persuade Innocent that it was enough if Abelard remained under the aegis of Cluny.
