c. 591 – 12 November 661 or 662), was an Irish bishop and fer léignid (lector) of Cluain Ferta Brénainn (Clonfert).
He early embraced a monastic state, and after some years was made abbot of Keltra, an isle in the lake Dergdarg, upon the river Shannon, sixteen miles from Limerick.
[2] He is famous for a Paschal letter (De controversia paschali) which displays his high level of learning.
[3] It consists of five manuscript folios, contains quotes from the Vulgate and Vetus Latina Bible; patristic commentary by Augustine, Jerome, Cyprian, Origen, Ambrosiaster and Gregory the Great; extracts from Canon law, ecclesiastical history and synodal decrees from Nicea and Arles in their original, uncontaminated forms, in addition to a decretum that enjoined on the Irish that, if all else failed, they should take their problems to Rome.
He also owned - among a library of at least forty manuscripts - ten Paschal tracts including one he attributed to "santus Patricius, papa noster" and possibly a letter of Pelagius.