Byzantine monk. As a young man, he entered the monastery of Studios in Constantinople, where he knew St Simeon the New Theologian. In 1053–4 he was involved in the controversy between Cardinal Humbert and Michael Cerularius which led to the mutual excommunications of 1054. His Life of Simeon is conceived as a defence of the institution of spiritual fatherhood, even in laymen, against the hierarchy. His spiritual teaching, contained in Three Centuries of Practical, Physical and Gnostic Chapters, is indebted to Simeon; like him he ascribes importance to the gift of tears.