AIDAN (or AEDAN ), a monk of Iona, and first bishop of Lin disfarne (A.D. 635-651). In 635 Oswald, who had succeeded to the kingdom of Bernicia in the previous year, re-united the whole of Northumbria under himself. Northumbria had been converted to Christianity by Paulinus (625-633), but had relapsed under the heathen successors of Edwin, and in 635 Oswald, who was an earn est Christian, sent for a new bishop. Paulinus had been a member of the Roman Church, but his successor was summoned from the headquarters of the Celtic church, the monastery of Iona, which Oswald had visited during his exile. The first monk sent was un successful; when he reported at Iona that he could do nothing with the uncouth Northumbrians, Aidan suggested that "he had not first given them the milk of mild doctrine . . . until they were able to understand the more perfect mysteries . . . of God." Thereupon it was decided to send Aidan as bishop to Northumbria.
True to the traditions of the Celtic church, he fixed his abode on the island of Lindisfarne. Under his influence, and that of the Irish monks who joined him, churches were built, and monasteries established, and a school founded where 12 boys were trained as preachers.
Christianity spread apace through Northumbria, partly because Aidan was building on the foundations laid by Paulinus, and partly because of the active support given by Oswald. There was a close friendship between king and bishop, and Bede tells us that when Aidan was preaching, Oswald, who understood Scottish, would often act as his interpreter. But the main cause of Aidan's suc cess was his own character; Bede, though disapproving of his observance of the Celtic Easter, gives him the highest praise for his learning, simplicity of life, and open-handed generosity. "What chiefly commended his teaching to all men was that it agreed with the life he and his followers led." The defeat and death of Oswald at Maserfield (Aug. 5, 642) did not destroy the Northumbrian Church; though the kingdom was divided, Aidan retained his see, and legend tells that his prayers saved Bamburgh from destruction by Mercian invaders. He died at Bamburgh, Aug. 31, 651, eleven days after the murder of his friend, King Oswin of Deira.
Aidan by his energy and saintly character had established in Northumbria Christianity in its Celtic form. But the phase was not lasting; in 664, at the Synod of Whitby, Oswy adopted the Roman Easter, and, abandoning the Celtic church with its mon astic ideal, brought Northumbria again into touch with the Chris tianity of Southern England and the Continent.
See Bede, Hist. Eccl. iii. 3, 5, 14-17, 25—Plummer's edition, with excursus on the Paschal Controversy; Oman, England before the Conquest (1921), ch. xiv. ; W. Bright, Chapters of Early English Church History (1897) chaps iv., v. See article EASTER.