The following is from Fr. Thomas Walsh's History of the Irish Hierarchy, published in New York in 1854, chapter lviii, at p. 617-18:
Clonenagh in the barony of Maryborough
St. Fintan of Clonenagh was the celebrated master of Comgall of Bangor. Fintan was a native of Leinster and son of Gabhren and Findath both of whom were Christians. On the eighth day after his birth he was baptized at Cluain mic trein which was probably in the neighborhood of Ross. His birth took place about the year 520. He received his early education under the holy man by whom he had been baptized and when of mature age he attached himself to St Columba, son of Crimthan, with whom he remamed until by his advice he established himself at Clonenagh about 548.
Young as Fintan was, his reputation for sanctity soon spread so that numbers of persons from various quarters of Ireland flocked to Clonenagh and became members of his institution. His monks not only lived by the sweat of their brows but cultivated the ground with the spade not having as much as a cow to assist them in their agricultural labors. The discipline of the house was exceedingly severe and the fasting seemed almost intolerable to some holy men. St. Cannech, among others on whose interference Fintan relaxed the discipline allowing milk to the monks, while towards himself he was unbending.
It is related that Cormac, a young prince, son of Dearmod, king of Hy Kinsellagh, was kept in chains by Colman, king of North Leinster, and who intended to put him to death, and that St. Fintan having gone with some of his disciples to the king's residence in order to procure the deliverance of the young prince, so affrighted Colman or Colum that he gave him up. This young prince, having afterwards ruled for a considerable time, ended his days in the monastery of St. Comgall of Bangor. Fintan was also gifted with a prophetic spirit an instance of which is stated to have happened on hearing an unworthy priest offering the holy sacrifice. Being horror struck at his impiety, the saint foretold that this unhappy priest would abandon his order and habit and, returning to the world, would die in his sins.
Columbkille is said to have had such an esteem for Fintan that he directed a young religious named Columbanus of the district of Leix, who was returning from Hy to Ireland, to choose him for his spiritual director and confessor. Accordingly, Columbanus waited upon him and related what the holy abbot of Hy had recommended. Fintan desired that he would not mention it to any other person during his lifetime and died very soon after. Before his death, which was somewhat prior to that of Columbkille, he appointed, with the permission and benediction of the brethren and of other holy men who had come to visit him, Fintan Maeldubh as abbot and successor at Clonenagh. Blessing his community and partaking of the body of the Lord he departed this life on the 17th of February.
His name is mentioned with particular respect in various Martyrologies both foreign and Irish. The year of his death is not mentioned, as is the case with other saints of Ireland, while the day is faithfully recorded. Natalis, which means a natal or birth day, is used to express the day of a saint's death because he then enters on a life that is everlasting. Other hagiologists say coepit vivere, he begins to live. Hence it is the day on which the memory of the saint is preserved, while the year of his death is omitted.
AD 625 died the abbot St Fintan Maeldubh. His festival is observed on the 20th of October
AD 830 the Danes destroyed this abbey
AD 866 died the abbot Laicten
AD 909 died Tiopraid bishop of this abbey
AD 919 again plundered by the Danes
AD 937 Ceallachan, king of Cashel, assisted by the Danes of Watorford, wasted the country of Meath, pillaged and sacked this abbey making the abbot a prisoner
AD 940 Ceallach, bishop of Clonenach, died
AD 970 died the bishop and abbot Muredach O'Connor
AD 991 died the abbot Diarmit, a professor of Kildare and a man of uncommon erudition
