No monastic community in the Middle Ages was as aggressive or successful in promoting the efficacy of the prayers of its brethren than the abbey of Cluny. Founded in 910 in Burgundy, Cluny upheld a rigorous standard of monastic conduct, a heavenly way of life that lent the prayers of its monks a powerful influence with God. Beginning in the second half of the tenth century, thousands of laypeople donated revenue-producing land to the abbey in exchange for prayers on behalf of the well-being of their souls (pro remedia animae). Around the year 1030, Abbot Odilo of Cluny (r. 994–1049) established a new observance on November 2, the Feast of All Souls, dedicated specifically to intercession on behalf of all departed Christians. On this solemn day, the brethren of Cluny celebrated masses, sung psalms, and gave alms to the poor in honor of the faithful departed.
The foundation of the Feast of All Souls was a bold and ultimately successful claim on the part of the Cluniacs that their prayers were more efficacious than those of other monastic communities for releasing the souls of the sinful dead from torment. To promote their community, the brethren of Cluny circulated a legend about the inspiration for establishing the Feast of All Souls. In the 1050s, a monk of Cluny named Iotsald composed an account of the virtuous life of Abbot Odilo, which included the story of a hermit, who witnessed the beneficial effect of Cluniac prayers on souls suffering at the hands of demons. According to Iotsald, the abbot allegedly founded the Feast of All Souls when news of the hermit’s story reached him at Cluny.
Concerning the vision of a hermit.
Lord Bishop Richard related to me the story of a certain vision, which I had heard once before but I could not remember the details. “At that time,” he said, “a certain devout man from the district of Rouergue [in southwestern France] was returning from Jerusalem. But when he had sailed halfway across the sea that stretches from Sicily to Thessaloniki, very strong winds struck his boat and drove it to an island, or rather a rocky outcropping, where a certain servant of God lived as a hermit. As he waited for a while for the sea to calm, the pilgrim tarried long enough to have a conversation with this servant of God about many different topics. Asked by the man of God where he was from, he responded that he was from the Aquitaine. Then the man of God asked if he had heard of a monastery called Cluny and if he knew Odilo, the abbot of that place. And the pilgrim responded, “I know the place and I know the abbot well, but I would like to know why you ask.” “I will tell you,” he said, “and I ask that you remember what you hear. There are places nearby from which, by the manifest judgment of God, a scorching inferno spouts with tremendous heat. In those flames the souls of sinners are purged by a variety of torments. A host of demons bear the task of perpetually renewing their torture; day in and day out, they heap more punishments upon the sinners, whose suffering grows more and more intolerable as a result. I have often heard them lamenting and making no small complaint, for the souls of the damned may be freed from their torments through the manifold mercy of God by the prayers of devout people and by the giving of alms to the poor, which occurs frequently in holy places. As you can imagine, they direct their strongest pleas not to be forgotten above all to the monks of Cluny and their abbot. For this reason, by God I beseech you, if you manage to return home safely, that you make known to the monks of Cluny everything you heard from me and you tell them on my behalf that they should apply themselves more and more to prayers, vigils, and the giving of alms for the relief of those souls trapped in punishment, so that through their good works joy may be multiplied in heaven to the detriment of the Devil.” When the traveler returned to his own country, he dutifully reported this story to the holy father Odilo and devout brethren of Cluny. Hearing this, they were in no small way amazed with a great joy in their hearts. Giving thanks to God, they augmented their prayers with yet more prayers, heaped alms upon alms, and immediately applied themselves to work so that the dead might find rest. It was on this occasion that the holy father Odilo established a new tradition throughout all of his monasteries. Just as the monks celebrated the Feast of All Saints on the first day of November, on the following day [November 2], they held a commemoration for the respite of all the souls of the faithful during which they celebrated masses privately and publicly with the singing of psalms and offered alms generously to all of the poor who came to the abbey. Through these good deeds, the Devil would lament greatly to lose what he thought he had and Christian souls in their suffering would rejoice at the hope of mercy.