The Coarb of Columba
In medieval Ireland and Scotland, the coarb of St Columba (Medieval Gaelic comarba Coluim Chille) identified the abbots who succeeded Columba. When the monks fled to their monastery in Kells, following the 9th century Viking raids on Iona, their abbot continued to hold the title of coarb to reflect his direct inheritance: many of the early abbots were members of Columba's family.
The abbot of the collegiate church (i.e. Celtic monastery following the Rule of St Columba), who held holy orders and said mass ('serveth the cure'), was responsible for his monastic community. In time, the pattern of a Bishop and an Abbot of Iona was established, which after the Reformation and the Dissolution of the Monasteries fell into disuse.
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