To give it the preeminence it deserves, we must refer to a subsequent event in the history of the Celts in Britain, since it happened there several centuries after Caesar, and we will quote the words of Augustin Thierry, who relates it:

"After the retreat of the legions, recalled to Italy to protect the centre of the empire and Rome itself against the invasion of the Goths, the Britons ceased to acknowledge the power of the foreign governors set over their provinces and cities. The forms, the offices, the very spirit and language of the Roman administration disappeared; in their place was reconstituted the traditional authority of the clannish chieftains formerly abolished by Roman power. Ancient genealogies carefully preserved by the poets, called in the British language bairdd - bards - helped to discover those who could pretend to the dignity of chieftains of tribes or families, tribe and family being synonymous in their language; and the ties of relationship formed the basis of their social state. Men of the lowest class, among that people, preserved in memory the long line of their ancestry with a care scarcely known to other nations, among the highest lords and princes. All the British Celts, poor or rich, had to establish their genealogy in order fully to enjoy their civil rights and secure their claim of property in the territory of the tribe. The whole belonging to a primitive family, no one could lay any claim to the soil, unless his relationship was well established.

"At the top of this social order, composing a federation of small hereditary sovereignties, the Britons, freed from Roman power, constituted a high national sovereignty; they created a chieftain of chieftains, in their tongue called Penteyrn, that is to say, a king of the whole, in the language of their old annals. And they made him elective.—It was also formerly the custom in Gaul. —The object was to introduce into their system a kind of centralization, which, however, was always loose among Celtic tribes."—(Conquete de l'Angleterre, liv. i.)

It is evident to us that if the Britons constituted a supreme power, when freed from the Roman yoke, it was only because they had possessed it before they became subject to that yoke. It is, therefore, safe to conclude that there was a supreme monarch in Britain and in Gaul as well as in Ireland; and since the Britons, after having lost for several centuries their autonomy of government, thought of reestablishing this supreme authority as soon as they were free to do so, it is clear that they attached a real importance to it, and that it entered as an essential element into the social fabric.

But what in reality was the authority of the Ard-Righ in Ireland, of the Penteyrn in Britain, of the supreme chief in Gaul, whose name, as usual, is not mentioned by Caesar?

First, it is to be remarked that a certain extent of territory was always under his immediate authority. Then, as far as we can gather from history, there was a reciprocity of obligations between the high power and the subordinate kings or chieftains, the former granting subsidies to the latter, who in turn paid tribute to support the munificence or military power of the former.

We know from the Irish annals that the dignity of Ard-Righ was always sustained by alliances with some of the provincial kings, to secure the submission of others, and we have a hint of the same nature in the passage, already quoted, from Caesar, as also taking place in Gaul.

We know also from the "Book of Rights" that the tributes and stipends consisted of bondsmen, silver shields, embroidered cloaks, cattle, weapons, corn, victuals, or any other contribution.

The Ard-Righ, moreover, convened the Feis, or general assembly of the nation, every third year; first at Tara, and after Tara was left to go to ruin in consequence of the curse of St. Ruadhan in the sixth century, wherever the supreme monarch established his residence.

The order of succession to the supreme power was the weakest point of the Irish constitution, and became the cause of by far the greatest portion of the nation's calamities. Theoretically the eldest son—some say the eldest relative—of the monarch succeeded him, when he had no blemish constituting a radical defect: the supreme power, however, alternating in two families. To secure the succession, the heir-apparent was always declared during the life of the supreme king; but this constitutional arrangement caused, perhaps, more crimes and wars than any other social institution among the Celts. The truth is that, after the heir-apparent, sustained by some provincial king, supplanted the reigning monarch, one of the provincial chieftains claimed the crown and succeeded to it by violence.