St. Odilo was a little man, of insignificant appearance and immense force of character; under him Cluny was at its greatest. Already in the days of St. Berno, Cluny had been something more than the normal self-governing institution envisaged in the Rule of St. Benedict. It had been linked with the abbey of Baume by St. Berno, who intended the union to continue. The idea was that each should help the other to maintain proper Benedictine practice. At the same time, the early abbots of Cluny were constantly called to reform other monasteries which, however, preserved their independence once the reform was complete. In many cases nothing further was neededthe English monastic reform undertaken by SS Dunstan, Ethelwold and Oswald under Cluniac influence is a conspicuous instance of Cluny's success by examplebut many reformed communities soon slipped back into their old ways. St. Odilo sought to prevent this by extending the original connection between Baume and Cluny very much further. He no longer merely reformed monasteries but subjected them permanently to Cluny; he appointed every prior of every Cluniac house, and the profession of every monk in the remotest monastery was made in his name and subject to his sanction. He periodically visited the monasteries subject to Cluny and saw to it that discipline was strict.
Consequently monasticism was given a greater stability, and there was never again any danger, as there had been since the days of Cassian and St. Benedict, of monasticism dying from internal corruption. What is more, Odilo had given the church its first religious order, properly so-called. Odilo left another legacy of a different kind. He started the practice of commemorating the dead of his order on the day after All Saints, so that it is from him that the celebration of All Souls' day has come down to us. He died in 1049 and was succeeded by St. Hugh, the sixth successive saintly abbot of Cluny.
Taken from "The Saints: A concise Biographical Dictionary", edited by John Coulson, published by Hawthorn Books, Inc. 1960.