He is called Saint Hugh the Great, and is one of the glories of the Benedictine Order. He was the adviser to nine Popes. One of his disciples was the monk of Cluny called Hildebrand, who after his election to the papacy was named Gregory VII, and is one of the greatest of the Popes.
For more on the Cluniac Reform, of which Saint Hugh was a part, “The Cluniac Reform: How Great Catholics Respond to Crisis.”
St. Hugh of Cluny, Emperor Henry IV, and Matilda of Tuscany (details)
