Saint Fursey was educated under Brendan the Navigator, Fursey later became a monk at the monastery of Clonfert, in County Galway, and was ordained priest. He later founded a monastery at Rathmat (probably in modern County Clare), which became one of Ireland’s major monastic centres. The extent of his apostolate is evident in places named for him in Galway, Louth, and Cork.
After 630, Saint Fursey left Ireland with his brothers Foillan and Ultán for Britain, where they were welcomed by the Christian king Sigeberht of East Anglia. They assisted Sigeberht and Felix in Christianizing the kingdom and in introducing monasticism. About 640, Fursey founded the monastery of Cnoberesburgh, near modern Yarmouth, Norfolk, which became the centre of his ministry. He sailed to Gaul some time between 640 and 644 and established himself in Neustria (in present-day Normandy), where he was well received by Clovis II. About 644 he founded a monastery at Lagny, near Paris. On a later journey he died, and afterward his body was transferred to Péronne, where his shrine became a great pilgrimage site; the monastery there remained an Irish centre through the 8th century.
Saint Fursey’s visions, which he was said to have experienced throughout his life, became widely known through accounts by the Venerable Bede in his Ecclesiastical History of the English People (8th century), which also contains the earliest life of Fursey, written by an anonymous contemporary monk; and by Aelfric Grammaticus (10th century). The visions included demoniac assaults, conversations with angels, divinations, and glimpses of heaven and hell; the accounts of visions influenced medieval vision literature, of which they are considered a prototype.