Columbanus

Columbanus (Irish: Columbán; 543 – 21 November 615) was an Irish missionary notable for founding a number of monasteries after 590 in the Frankish and Lombard kingdoms, most notably Luxeuil Abbey in present-day France and Bobbio Abbey in present-day Italy. Columbanus taught an Irish monastic rule and penitential practices for those repenting of sins, which emphasised private confession to a priest, followed by penances imposed by the priest in reparation for the sins. Columbanus is one of the earliest identifiable Hiberno-Latin writers.

Notable works: De mundi transitu, Letters

Source: Wikipedia — https://en.wikipedia.org/wiki/Columbanus