Григорий XI
By the 14th century the monastery had entered a decline, and in 1373 was granted to the Carthusians of Pisa Charterhouse by Pope Gregory XI, under the influence of Saint Catherine of Siena. The Benedictines were banned from the island. Unusually, the prior of the new charterhouse inherited from his Benedictine predecessors the title of abbot, and the charterhouse that of abbey.