An interesting proof of the antiquity of this material has been discovered by the acuteness of Dr. MacCarthy. Patrick’s dealings with the sons of Forat in Múscraige Tíre are described in _Vit. Trip._ 210, and indicated in _Lib. Arm._ f. 19 rᵒ b (351₃: Fuirg Muindech Mechar, f. Forat). Patrick is alleged to have given a lasting blessing to Mechar, who believed, whereas Fuirg, who did not believe in him, is “to be in misery till doom.” Dr. MacCarthy has pointed out that these prophecies are inconsistent with the history of the descendants of both brothers. The seed of Mechar did not survive. We learn this from the Genealogy of Múscraige Tíre (in _Book of Ballymote_, 141 b, and _Book of Leinster_, 323 f.; extracts in MacCarthy’s paper).[292] Dr. MacCarthy thinks that the extinction of the line is to be placed about the middle of the sixth century. On the other hand, the descendants of Fuirg prospered; they were a distinguished and important clan in the ninth and tenth centuries (see the evidence which Dr. MacCarthy has collected from the _Annals_, Note D.). The inference is that the record of Patrick’s dealings with the sons of Forat had taken shape before the respective destinies of the posterities of Mechar and Fuirg could be foreseen. 3. _Life of Patrick, by Muirchu_ The first formal biography that we possess, perhaps the first formal biography that was written, was composed by MUIRCHU towards the end of the seventh century. Muirchu is designated as _maccu Machtheni_, son or descendant of Machthene. He refers to his father Coguitosus,[293] and there may be room for doubt whether a natural or spiritual father is meant. If the suggestion[294] that Coguitosus is a Latin rendering of Machthene (as connected with _machtnaigim_, “I consider with wonder”) is correct, Cogitosus was Muirchu’s father in the flesh. There can be no doubt that Muirchu lived in North Laigin, and perhaps he may be specially associated with Co. Wicklow. The evidence is (1) his close association with Bishop Aed of Slébte (on the borders of Co. Carlow), to whom he dedicated his book, addressing him _mi domine Aido_, and from whom he derived material for it; (2) the existence of Kilmurchon “Church of Muirchu” in Co. Wicklow;[295] and, we may add (3), the connexion of Muirchu’s “father” Cogitosus with this part of Ireland, a connexion fairly to be inferred from his writing a Life of Brigit of Kildare. The fact that Muirchu lived and wrote in the latter part of the seventh century is established by the date of his friend Bishop Aed’s death, which is recorded in the _Annals_ as A.D. 700,[296] and by the circumstance that he as well as Aed attended the Synod known as “Adamnan’s,” which met shortly before that date (A.D. 697, _Ann. Ult._).[297] As Muirchu’s book is dedicated to Aed (as still living), A.D. 699 is the lower limit for its composition.