PETER MONOCULUS, Blessed. — Cistercian, relative of Philip II, King of France, born in the castle of Marlac near Cluny, died at Foigny on 29 October 1186.
A monk of Ingy, he became abbot of Valroy in 1169, where he lost an eye (hence the name Monoculus) due to illness; later abbot of Ingy, in 1179 abbot of Clairvaux. He was zealous for monastic discipline and performed various miracles. Always humble and amiable, he was highly esteemed by Popes Alexander III and Lucius III, Emperor Frederick Barbarossa, and King Philip II of France.
Sixteen of his letters survive, including notable ones addressed to Alexander III, the Chancellor of the Holy Roman Church, the Archbishop of Mainz, and the Bishop of Winchester, as well as to the King of Portugal and the cardinal-bishops of Albano and Palestrina (PL 201, 1393–1404). From the 13th century onward, he has been venerated as a blessed within the Cistercian Order, whose Menology commemorates him on 18 May.