As the errors of this writer, though so long before the public, have never been sufficiently exposed, I shall here undertake the task, by the exhibition of a few examples of his process of investigation, taken without selection, and given as a fair specimen of the whole. It will be necessary for me, however, in fairness, to quote in the first instance the author’s own account of the theory which he has put forward to account, in his novel manner, for the origin of the names of men and tribes in Ireland.
“On the increase of population and the introduction of agriculture, these wandering tribes were under the necessity of confining themselves to certain permanent districts; which districts were generally denominated either from their situation or quality of the soil, and from which also the inhabitants obtained their collective appellation; whence, in the most ancient Irish poems and histories, we frequently find _clan_ and _slioght_ added to the _name of the country_, to signify the inhabitants; as _clan Cuilean_, _slioght Breoghain_, and _slioght Gae_; wherefore _the children and race of any division_ were the invariable names by which the ancient Hibernian septs were distinguished from the remotest antiquity, and not, as frequently asserted, the children and descendants of their respective leaders.”
Again, “The chiefs of every district were elected from the elder branches of the dynasts; and the kings of the principalities from the senior chief of the subordinate districts, who on their advancement to the dignity obtained the name of the district or clan over which they presided; it being an universal custom amongst all the Celtic tribes to denominate the noblesse, with their other appellations, from the place of their residence; a custom in some measure yet retained in the Highlands of Scotland. The variety of names used by the ancient Irish have occasioned great confusion in their history; for before the tenth century surnames were not hereditary, and prior to the establishment of the Christian religion in this country no person was distinguished by one permanent nomination. It is true, during their pagan state every child at his birth received a name generally from some imaginary divinity _under whose protection he was supposed to be; but this name_ was seldom retained longer than the state of infancy, from which period it was generally changed for others arising from some perfection or imperfection of the body, the disposition and qualities of the mind, achievements in war or the chace, the place of birth, residence, &c. so that it frequently happened that the same person was distinguished by several appellations. Our ancient historians, not properly attending to this, have committed great errors in relating the transactions of early periods, by asserting the same action to be performed by several different people, which in reality was performed by one only, thereby throwing their history and antiquities into too distant a period. A similar error has also been committed by not considering the dignitary names of the chiefs, who on their election to the government constantly obtained the name appertaining to the clan over whom they presided, or rather that of the district. These dignitary names becoming in the tenth century hereditary and family distinctions, created new difficulties to genealogists of latter ages.”--Collectanea, vol. iii, p. 257.