For twenty-eight years he lived the ascetical life on Mt Athos as a disciple of St Gregory of Mt Sinai. Later, he founded the monastery of St Mamas, also on Mt Athos. In 1350 he was elected Patriarch of Constantinople. After four years, he resigned the patriarchal throne to return to the Holy Mountain, but was called back to the throne, where he remained until his death in 1363. He wrote the definitive lives of St Gregory the Sinaite and St Theodosius of Trnovo. He was known to St Maximos Kapsokalyvia (the Hut-burner), who foretold his death: On his final journey to Serbia, on which he died, the Patriarch stopped on Mt Athos, where St Maximos saw him and said, "This elder will not see his flock again, because I hear behind him the hymn over the grave, 'Blessed are those that are undefiled in the way...'"