The Book of Invasions, of which a convenient summary is given by Keating, forming the first part of his history, is in its true aspect a national epic which took shape gradually in the early Christian period and under the influence of Christian and Latin learning. It treats the principal elements of the ancient population, both Celtic and Pre-Celtic, as offshoots of one stock, united in ancestry, and it thus symbolises the effective national unity and fusion which had come about. The land of Ireland is the unifying principle, and all the children of the land are joined into one genealogical tree. Some recent writer, I think it is Mr. George Moore, has remarked how Irish people, apparently quite naturally and unconsciously, speak and think of their country as a person. This they have been accustomed to do through all the ages of their literature. The first words spoken by a Gael on Irish soil, in the ancient legend, were an invocation addressed to Ireland herself by the druid Amorgen: "I entreat the land of Eire," and the land itself, under its three names, Éire, Fódla, and Banbha, when the Gaels arrived, was reigning as queen over the Men of Ireland. Thus we find the clearly formed idea of one nation, composed of diverse peoples, but made one by their affiliation to the land that bore them--the clearest and most concrete conception of nationality to be found in all antiquity. IV. THE FIVE FIFTHS OF IRELAND We have seen how the poet-historians of early Christian Ireland took over certain Latin histories of the world, especially St. Jerome's translation of Eusebius and the history of Orosius, and adopted these as the established framework of the world's history, thereby compelling themselves to adjust their own accounts of the Irish past to that framework. In the process of adjustment they did not all work hand in hand, and so we have different and sometimes contradictory accounts and at least half-a-dozen distinct chronologies. They found a mass of Irish traditions and legends embodied in stories long and short. They set to work on this material, endeavouring to arrange it all in sequence and to provide it with dates--the original matter being largely independent of date or sequence. This task became in fact the principal work of a certain school or class of poets, as we learn from a passage which, though found in the Book of Leinster, is held to date from about the eighth century. It is headed: "Of the Qualification of Poets." The word translated "qualification" by O'Curry, and not inaptly so translated, is _nemthigud_, derived from the word _nemed_, the Old Celtic adjective _nemetos_, meaning "sacred." A sacred place was called _nemed_, and a sacred person was also called _nemed_. The old law tract which deals with the privileges and rights of the poets is entitled _Bretha Nemed_, i.e., decisions regarding sacred persons. The tract in the Book of Leinster tells us that certain kinds of knowledge were necessary qualifications