Celestin Cellach
Cellach, Celestin, or Celsus, was consecrated Archbishop of Armagh, 23rd September 1106, when only twenty-seven years of age. His Irish title was MacAid MacMaelisa. He took a leading part in the ecclesiastical affairs of his time. In 1125 he repaired the cathedral at Armagh. The latter part of his life was occupied in reconciling differences between the princes and great men of the kingdom. In 1128 he arranged a truce between the Kings of Connaught and Munster. He died at Ardpatrick, County of Limerick, 1st April 1129, aged about 50, and was buried at Lismore. It is supposed that he once presided over the see of Dublin. The Church was in a very corrupt state in his day: "By his exemplary conduct, charity, preaching, erecting of churches, laying down rules of discipline and morality for the clergy and people, and other pastoral exercises, [he] greatly contributed to bring about a better order of things."
Sources
119. Ecclesiastical History of Ireland: Rev. John Lanigan. 4 vols. Dublin, 1822.
118. Ecclesiae Hiberniae Fasti: Rev. Henry Cotton: Indices by John R. Garstin, M.A. 5 vols. Dublin, 1851-'60.
339. Ware, Sir James, Works: Walter Harris. 2 vols. Dublin, 1764.