Archbishop of Armagh 1105–29.
The last of a long line of archbishops of Armagh, chosen as laymen by hereditary succession, Celsus proved a notable reformer. He is known mainly through the Lives of his protégé and successor, Malachy. As co-arb of Patrick he travelled over many parts of Ireland, collecting dues, finding out the general state of the Church and implicitly asserting the rights of Armagh. He presided over the reforming Synod of Rath Bresail in 1111 with Gilbert of Limerick, the papal legate, when normal diocesan and metropolitan organization was set up and various liturgical reforms promulgated. This council, whose conclusions were not always well received, aimed at bringing the Irish Church into line with others in western Europe. Celsus rebuilt Armagh cathedral, and was often in demand as a peacemaker between warring Irish kings. He promoted Malachy, first as his own archdeacon, later as bishop of Connor, and finally as archbishop of Armagh, thus breaking the line of hereditary succession. Feast (in R.M.): 1 April; more generally in Ireland, 7 April.
AA.SS. Apr. I (1675), 619–20;The Irish Saints (1964), pp. 62–7;H. S. Lawlor, St Bernard of Clairvaux's Life of St Malachy of Armagh (1920).