St Finnian of Clonard died, according to the Annals of Ulster, in 549. With the possible exception of the sixth, seventh and eighth century annal entries and of the Catalogus Sanctorum all the evidence for a study of his work dates from or after the ninth century. It is however possible to say with reasonable assurance what traditions of his life were accepted about three hundred years after his death, and to trace the development of his cult from the late eighth century onwards.
St Finnian's Irish Life gives the most primitive account now extant of his career. All manuscripts go back ultimately to the same original, which was compiled by a Leinsterman writing in Leinster, almost certainly a monk of one of Finnian's foundations, possibly Clonard, who drew on both oral and written traditions for his material. The Life is an unsophisticated collection of miracle stories, combined with extravagant claims concerning the spiritual power and prestige of the saint, and giving full particulars, including a considerable amount of accurate information on local topography, of the churches which Finnian is reputed to have founded.