In Gaul the institution of kingship was already in rapid process of dissolution in Caesars time. But among the insular Celts it proved more enduring, and in Ireland and Scotland its decline coincided with that of the entire Gaelic social system, which finally foundered in the seventeenth century. Indeed, to the Irish mind kingship and the public weal were so intimately related as to be at times almost synonymous, and in the deep misery of the eighteenth century when the poets lamented their countrys servitude to a foreign oppressor and wishfully prophesied the return of the old order, it was always in terms of the restoration of the native kingship that they envisaged the great liberation. Since the Irish nobility had already been destroyed or dispersed throughout the armies of Europe, it was to the exiled Stuarts that the poets turned - faute de mieux - for a symbol of their deliverance. In the circumstances of the time, it was a gesture almost entirely devoid of political reality, but it was delivered with much eloquence and, above all, with a profound sense of tradition, for in thus making Irelands salvation conditional upon the accession of a rightful and acceptable king, they were acting as the faithful transmitters of an age-old and uninterrupted belief.
However, paradoxically as it may  appear, the earliest recorded tradition, namely the Laws, knew no king of Ireland, but only the king of a tuath (the basic territorial unit) and the king of a province. The notion of a king of Ireland with actual powers over the whole country is attested commonly in the literature but nevertheless it seems to be relatively late and to have been propagated from the ninth century onwards by native historians and learned poets working in the interest of the great dynasty of the Uí Néill, the descendants of Niall of the Nine Hostages.
And yet it cannot be wholly a new creation. For one thing, the king of Ireland was also known frequently as king of Tara, and there is no lack of evidence to show that Tara must have been a sacred site of kingship from time immemorial. It was situated within the central province, Midhe, which was itself enclosed by the other four provinces of the pentarchy, thus forming a cosmographic schema which has parallels in Indian and other traditions. The very word for a province, cóigedh, literally a fifth, presupposes a transcendant unity at the heart of which stands Tara, and, as Alwyn and Brinley Rees have pointed out, the traditional accounts of the disposition of the court of Tara show that it was conceived as a replica of this cosmographic schema.
Tara was also the site of the famous Feis Temhra, The Feast of Tara, which was held in pagan times to confirm or legitimise the recently elected king and during which, it would seem, his ritual marriage to the realm was celebrated (the word feis means both feast and to sleep, spend the night): as the early triad has it, the Feast of Tara was one of the three things that hallow a king. On the Hill of Tara stood the Stone of Fál, the stone penis which cried out when it came in contact with the man destined to be king. Since Fál is commonly used as a poetic or learned synonym for Ireland , obviously the kingship myth attaching to the Stone of Fál had a universal reference. While it does not follow from this that the king of Tara in the pre-Christian era held political sway over the whole of Ireland - otherwise this would no doubt have been recognised in the Laws - it is clear that he enjoyed a special prestige by virtue of his position at the sacred focus of kingship.
Kingship was heritable within a family group (the derbhfhine ) comprising four generations: all living members of this group were potential successors and it was from their number that the new king was elected. But Irish tradition also knows of more ritual modes of selection. The first comprises several  ordeals to test the candidates fitness: a royal chariot that actively rejected him who was unworthy; a royal mantle that proved too big for him; two stones, with but a hands breadth between them, which opened wide to give passage to the chariot of him who was found acceptable; and finally, of course, the Stone of Fál which clearly voiced its assent. The second mode of selection was known as the tarbhfhess, bull-feast, or bull-sleep: a bull was killed, and a man ate his fill of its flesh, drank its broth and then lay down to sleep, and after an incantation had been chanted over him by four druids he saw in his sleep whoever was destined to be king. Both these methods of selection are expressly associated with the kingship of Tara, and it may be that they represent rituals once performed at the central seat of kingship.
A general feature of sacral kingship is the tendency to insulate the person of the king against the perils of the profane world and to regulate his conduct down to the merest details. A striking instance of this in Irish usage is the series of magically binding prohibitions ( geissi ) to which he is subject simply by virtue of his office. The particular significance of these geissi is in most instances obscure: some may allude to circumstances that have once proved harmful and are therefore to be avoided, while others might seem wholly arbitrary. Thus the king of Ulster is forbidden to take part in the horse-race of Ráith Lini, to listen to the birds of Lough Swilly when the sun sets, to taste the flesh of Dáires bull, to go into Magh Cobha in March and to drink the water of Bé Nemhidh (a river) between dawn and darkness. What is clear, however, is that they relate to his sacral status - as, for example, do the rather similar interdictions attaching to the office of the Roman Flamen Dialis - and whenever fate impels him to violate them this is a clear portent that his kingship, and indeed his life, is at an end. Whether it was ever the practice in certain circumstances to set a term to the kings reign by subjecting him to a ritual death such as is attested in other societies cannot be demonstrated beyond doubt, but several episodes in early narrative indicate it as a definite possibility.
The qualities of a rightful king (which in Irish are comprised under the term fir flaithemhan, literally truth of the ruler) are reflected in the condition of his kingdom. They ensure peace and equity, security of the kingdoms borders, and material prosperity: the trees bend low with the weight of their fruit, the rivers and the sea teem with abundance of fish, and the earth brings  forth rich harvests. Conversely, a king who is blemished in his conduct and character or in his person will bring about corresponding privations: for this reason Bres was deposed, since he was completely lacking in the princely virtue of liberality, and Nuadhu was obliged to abdicate once he lost his arm in battle. Cautionary instances were numerous and familiar, such as that of the usurper Cairbre Caitchenn, during whose reign there used to be but one grain on each corn-stalk and one acorn on each oak, and the rivers were without fish and the cattle without milk. In Welsh the same notion is at the origin of the sudden desolation of Dyfed in the Welsh tale of Manawydan, and in the Grail legend it recurs still more explicitly in the waste land which results from the maiming of the Fisher King.
The sacral king is the spouse of his kingdom and his inauguration ceremony is known as banais ríghi, weddingfeast of kingship; in other words he is then ritually united with the sovereignty of the territory over which he rules. This is why the Feast of Tara could not be convened and Eochaidh Airemhs kingship ratified until he had sought out Édaín to be his queen: otherwise he would have been the supreme paradox of a king without sovereignty. As queen of Connacht, the goddess Medhbh required that her husbands be without niggardliness, without jealousy and without fear, that is to say, they must possess the paramount attributes of a king. As Medhbh Lethdherg of Leinster, her other manifestation, she cohabited with nine kings of Ireland and of her was it said: Great indeed was the power and influence of that Medhbh over the men of Ireland, for she it was who would not permit a king in Tara unless he had her for his wife. Mór of Munster was spouse to two kings of that province and she was sought after by the kings of Ireland .
The wedding ritual of the banais ríghi evidently comprised two main elements, a libation offered by the bride to her partner and the coition. The Sovereignty of Ireland appears to Conn of the Hundred Battles seated on a crystal throne and with a vat of red liquor beside her from which she serves him (and his successors) with a drink in a golden goblet, and the same essential function is implied in the name of the goddess Medhbh, The Intoxicating One. The sexual element is almost always present, whether explicitly or by implication, and one of the normal ways of reporting the inauguration of a king is to say that he was wedded to (literally slept with) his kingdom.
As a result of this union the person of the goddess is sometimes utterly transformed. Just as the land lies barren and desolate in the absence of its destined ruler and is quickly restored to life by his coming, so the goddess who personifies the kingdom often appears ugly, unkempt and destitute until united with her rightful lord, when suddenly she is changed into a woman of shining beauty. One such tale is told of Niall Noighiallach. He and his four brothers go hunting, find themselves astray in the wilderness and stop to cook part of the game they have killed. Each in turn goes off to look for water and comes upon a well guarded by a hideous crone who will give water only in return for a kiss. Three of the brothers refuse outright, Fiachra grants her a fleeting kiss, while Niall not merely kisses her but consents to lie with her as well. Immediately she is transformed into a young girl more radiantly beautiful than the sun. She is, she explains, the sovereignty of Ireland and she foretells that Niall and his descendants will hold unbroken rule, apart from two kings of the posterity of Fiachra who were foretokened by his brief kiss.
This particular adaptation of the kingship myth is intended to account for the centuries-long hegemony of the Uí Néill, Nialls descendants, over the  greater part of the country. It has a parallel in the Munster legend told of Lughaidh Laoighdhe, an ancestor of the pre-Goidelic people known as the Erainn and, almost certainly, an avatar of the god Lugh. Here the brothers quarry is a magic fawn which is evidently another metamorphosis of the goddess: by capturing it, as well as by sleeping with the hag, Lughaidh marks himself out as future king. This fawn of sovereignty is a forerunner of the magic stags which appear in the story of Perceval and in other Arthurian romances.
It need hardly be stressed that the sacral kingship and the sacred marriage of king and goddess are not peculiarly Celtic, the former being more or less universal and the latter well attested from India and the Near East. What is remarkable, however, is the persistence and vigour of these concepts in the tradition of the only Celtic society which remained relatively untouched by Roman civilisation (and that they were also present in British tradition is evident from their prominent role in the Arthurian legend). They profoundly influenced the telling and the writing of Irish history and doubtless they contributed much to its making. One may reasonably wonder, for instance, whether Boudica of the British Iceni or Cartimandua of the Brigantes would have figured so prominently in history but for the fact that the Celts venerated a sovereign and dominant goddess variously known as Medhbh, or Macha, or Brigantia.
And Irish kings were no less aware than their poet-propagandists of the action of myth on history. The ninth-century king of Munster, Feidhlimidh mac Crimthainn, had designs on the lordship of Ireland, and according to some Munster sources he did in fact achieve his aim. In 838 A.D., report the Annals of Innisfallen, he obtained the submission of Niall Caille, king of Tara, and two years later he raided northwards as far as Tara and seized Gormlaith, Nialls queen, together with her female retinue. It is hard to believe that Feidhlimidh did not have an eye to tradition when he thus abducted Queen Gormlaith from the sacred seat of kingship, for in the Irish context his action must surely have implied that just as he had taken possession of Nialls spouse of flesh and blood so also was he in virtual possession of that other spouse to whom Niall laid claim, namely the sovereignty of Ireland.
The concept of the land of Ireland as a goddess was deeply rooted and it did not die easily. When the Gaels first set foot on its soil, so the legend tells us, they were met by the lady Ériu, queen and eponym of the island, and ages later when Gaelic society had been broken by plantation and by the sword, the poets of the seventeenth and eighteenth century still pictured their land as a woman languishing in yearning for her absent spouse, or even as a shameless prostitute granting her favours to the boorish foreigner who had usurped the place of her rightful partner. And finally from these Gaelic poets of the hidden Ireland the concept was borrowed by various individual poets of Anglo-Ireland, and notably by the greatest among them, W. B. Yeats. The ring of tradition is clear and loud in the final words of his play, Cathleen Ni Houlihan, at that point where the mysterious old woman of the roads has just gone from the house: Did you see an old woman go ing down the path? Peter Gillane asks his young son Patrick - and the answer is: I did not, but 1 saw a young girl, and she had the walk of a queen.