Myles Dillon & Nora Chadwick, The Celtic Realms [History and Civilisation] (London: Weidenfeld & Nicholson 1967)
Chap. 7: Celtic Religion and Mythology and the Literature of the Otherworld
The Celtic world is exceptionally rich in memories of religion, mythology and the supernatural. In Gaul religious life was evidently very intense. Ireland has preserved the richest store of mythological traditions of any country north of the Alps, not even excepting Iceland. Yet the evidence for the supernatural conceptions for these two Celtic realms is somewhat paradoxical, and disparate. Gaul has much to tell us of the religion of the Celts. We have already seen in chapter I that memories of the ancient Gaulish gods and spirits have survived in innumerable dedications at local sanctuaries of rivers and springs, sacred lakes and forests. Many records have survived in the writings of Classical authors, in place-names, and in material remains in metal-work, in coins and inscriptions. Native Celtic temples of the late Classical period have been excavated, and statuary in both wood and stone now witnesses to a native Gaulish conception of the gods in human form at least from early in our era. Our knowledge of religion in Gaul as a living belief and practice is therefore considerable.
On the other hand in Gaul, as in ancient Greece and the Teutonic world, there is no close connexion between religion and mythology, as the mythology has come to us in later and more fully developed stages. Mythology is always to some extent an artificial creation, an artistic expression of religious emotions or beliefs which are in the nature of things formless. Mythology is, in fact, an attempt to define the infinite and the indefinable, and what it offers is not a definition but a symbol. The mythology of the Gauls, the artistic symbolism of their religion, has not survived, owing to the fact that no Gaulish literature has survived. Their oral traditions, including their mythology, were never written down. As a result of the Roman conquest Gaul rapidly adopted Roman culture, including the art of writing, and the oral traditions died quickly.
In contrast to this, the oral literature of ancient Ireland, including the mythological traditions, survived, as we have seen, till a much later period. The archaism of Irish culture, virtually untouched by Roman culture till nearly half a millennium later than Gaul, preserved its oral  traditions intact, including its mythological traditions, till the art and fashion of writing had become general in the Christian monastic scriptoria, from the sixth century AD onwards. The heathen religion was by this time a thing of the far past, and the Christian monasteries had no will to record it. For Gaul we have a wealth of evidence for Celtic religion but no developed system of mythology. For Ireland we have a wealth of mythological tradition in a highly developed literary form, but practically no evidence directly bearing on heathen religion.
Yet the hiatus is more apparent than real. Celtic Britain forms a bridge between the two Celtic realms of Gaul and Ireland. In material remains she has much in common with Gaul from which she has been directly influenced; in mythological traditions she has retained fragments which can be shown to be identical in origin with those of Ireland. Owing to the Roman conquest of Britain both material remains and mythological traditions are relatively sparse; but they are both relevant and valid, and we shall refer to them briefly here, to demonstrate both the fundamental unity of Celtic religion and mythology and also the essential unity of the Celtic realms in their heathen spiritual life. 
As late as the sixth century AD the Byzantine writer Procopius has left us a remarkable echo of the Western World as the last home of the traditions of the Celtic lands of the Continent. He tells us that the people of Armorica had the task of conducting the souls of the dead to our island. In the middle of the night they heard a knocking on the door, and a low voice called them. Then they went to the sea-shore without knowing what force drew them there. There they found boats which seemed empty, but which were so laden with the souls of the dead that their gunwales scarcely rose above the waves. In less than an hour they reached the end of their voyage, and there in the island of Britain they saw no-one, but they heard a voice which numbered the passengers, calling each by his own name. Breton folk-lore has located the place of departure as the Baie des Depassés on the south-western tip of Brittany. (Procopius Gothic War, VIII, xx, pp.45-49.)
Quotes Lucan’s Pharsalia: ‘[druids] who dwell in deep groves [nemora alta] and sequestered uninhabited woods’, and who ‘practise barbarous rites and a sinister mode of worship’ to which the scholiast adds: ‘They worship go the gods in woods without making the use of temples.’ (H. Usener, Scholia in Lucanem, 1869, p.33 [10th c. MS]) 
Caesar never methions temples in Gaul, although Suetonius accuses him in vague terms of having robbed Gaulish fana and templa. (Suetonius, Caesar, 54.)
The structural plan of the many native Celtic stone-built temples from the Roman period in both Gaul and Britain remains constant, though there is some variety in shape. The normal form was a square box-like building consisting of a cellaor sanctuary, sometimes raised and surrounded by a portico or verandah, which might be closed or with low walls designed to carry columns. The cella was small, entered by a door, and lighted by small windows above the portico, and the public were evidently excluded from the cells. The whole was sometimes contained in a square enclosure. Both in Gaul and Britain, however, both round and polygonal temples existed while retaining the same scheme of cella surrounded by a peristyles. (Suetonius, Caesar, 136 f., 194.) 
Irish mythology is derived through the Atlantic sea-routes from a much earlier age than our earliest mythological records. From the time of Vergil to the fifth century AD the proud Romans used to refer to the Celtic peoples as living ‘beyond our World’, ‘on the edge of the habitable globe’. They meant that the Celtic peoples were beyond the limits of the civilization of Greece and Rome. The Classical civilization was a world to itself, a civilization raised to great heights in an incredibly short time by the introduction and spread of the art of writing. Already by the fifth century AD the Roman system of education had spread to Britain, and boys were being sent to school as a matter of course to learn writing. But under this Classical civilization with its written texts there lay another civilization rich and brilliant. Its stories and poems, and all its accumulated native tradition were carried on by word of mouth. This was the intellectual life of the Iron Age, dating from the seventh century BC or earlier. In the Mediterranean countries it gave way to Classical culture; but in Gaul, this earlier native Celtic culture persisted throughout the Roman period, and formed a remarkably interesting combination, Gallo-Roman culture.
Beyond Roman Gaul, however, the ancient Celtic culture of the Iron Age remained in cold storage, virtually untouched by Roman influence. This is the ancient native civilization of Ireland with her traditions intact from the Iron Age, like an unwritten manuscript of the ancient Celtic world. Ireland is the only Celtic country which has preserved a great wealth of ancient mythological stories.
Irish mythology is a great contrast to Greek mythology because the  gods were not organized in early times by the poets into a great heavenly community like the gods of Olympus. They never live in the sky or on the mountain tops. They live individually either underground or on the earth, often across the seas or on distant islands.
The ancient mythological stories of Ireland may be divided into four chief groups. We do not include here stories of local cults of springs and rivers and lakes, such as are prominent in Gaulish religion. These are not prominent as independent cults in Ireland, and occur chiefly – and not even very commonly – in connexion with important gods, such as the Dagda, whose home was Bruig na Bóinne, close to the Boyne.
Group 1 is of the older Celtic gods, who are known from early times in Gaul, and also, perhaps later, from Britain.
Group 2, a much larger group, the native Irish gods of underground, whose homes are in the síd-mounds, the great barrows of the dead. This is the group of whom the majority of our most picturesque stories are told. They are by far the best known to modern scholars.
Group 3, the gods of re-birth, also known from sources outside Ireland, and not originally, or at least obviously, associated with the síd-mounds, but with the sea.
Group 4. Stories of the supernatural world – Tír Tairngiri, ‘the land of Promise’; Tír na nÓc, ‘the land of the Young’; Mag Mell; and stories of mortals who visit it. These are commonly referred to as echtrai, ‘adventures’ and baili, ‘visions, ecstasies’.
It is natural to suppose that the earliest gods are those who belonged originally to the ancient Celts of Gaul. Perhaps the chief was the god Lug who has already been discussed. His name, as we have seen, has survived in many place-names in Gaul and possibly Britain. Various stories have survived as to how he came to Ireland; but his foreign origin is recognized by early allusions, for he is said in one story to come from overseas, and he is referred to as a scál balb, a ‘stammering spirit’, doubtless with reference to his foreign tongue. In Wales his name is cognate with that of Lleu Llaw Gyfes who is a prominent hero in the Mabinogi of Math fab Mathonwy. But he has been integrated with the Irish pantheon, being claimed as the originator of the Fair of Teltown, held a fortnight before the Festival of Lugnasad on the first of August and a fortnight after it, resembling the Olympic games. He was fostered and trained by the wife of one of the Tuatha Dé Danann till he was fit to bear arms. This training in martial accomplishments by a woman is an interesting allusion to an early Celtic traditional custom, to which we shall refer later.
The triad of the ancient Gaulish dividints, the matronae (L. matres) has also survived in the three mother goddesses of  war in Ireland - the Mórrígan (‘great queen’) and Macha and Bodb, the essentiay goddess of battle - perhaps also the three Brigits. Mórrígan, is one of the the early pan-Celtic divinities, and is also apparently the forerunner of Morgan la fée of the Arthurian cycle, and is said to have had a union with the Dagda a year before the battle of Moytura. She is an unpleasant person. The Annals of Tigernach have preserved s.a. 622 an ancient fragment of an elegy of a Leinster prince who was drowned in his little curach:
The deep clear depths of the sea and the sand on the sea-bed have covered them. They have hurled themselves over Conaing in his frail little curach. The woman has flung her white mane against Conaing in his curach. Hateful is the laugh which she laughs today.
The white-haired woman with her hateful laugh is the Mórrígan who has drowned the prince with the white breakers (vide O’Rahilly, EIHM, 314; also Thurneysen, Morrígain = queeen of phantoms / Maren-königin, Heldensage, 63). We may think of the Coire Brecain referred to in Cormac’s Glossary, ‘the Cauldron of the Old Woman’, the well-known whirlpool, the Corry-vreckan, between the northern end of Jura and the Isle of Scarba in the Inner Hebrides.
Another goddess attested by inscriptions both in Gaul and Britain is the goddess Brigit (cf. the name of the Brigantes in N. England). The late Irish text, the Lebor Gabála, represents her as the daughter of the Dagda, greatest of the Irish native gods. According to the story in Cormac’s Glossary she is the patron of poets while her two sisters are goddesses of smiths and of laws. She appears to have been Christianized as St Brigit, whose shrine is at Kildare, where her sacred fire was kept burning.
The earliest native Irish gods, those included in Group 2 above, live underground, occasionally in caves, more often in the prehistoric tombs of the ancient dead chieftains. The most famous of these is Brúg na Bóinne [Plates 44, 46], one of three great beehive-shaped tombs, like the so-called ‘Treasury of Atreus’ in Greece. It is now called New Grange and is lit by electric light, so that it is possible to see from inside the impressive corbelled dome [Plate 45]. These gods of the underworld are called aes síde (sing. síd), and their homes, the burial-mounds, are síde. The most interesting of these is Brí Léith, near Ardagh in Co. Longford, the home of the god Midir, who had been the fosterer of the god Oengus mac Oc, son of the Dagda and Boann.
The Dagda is the most prominent of the older chthonic gods. His appellation, name means literally ‘the good god’; but the epither does not imply that he is ‘good’ in the moral sense. ‘The good dog’ is not a name, but an appelation, an epithet. When the Dagda’s turn comes to state his qualification in the council of war before the battle of Moytura he declares:
‘All that you promise to do I will do, myself alone.’
‘It is you who are the good god,’ they say. And from this day he is called the Dagda, i.e. ‘good for everything’ - a leading magician, a redoubtable warrior, an artisan - all powerful, omniscient. He is Ruad Ro-fhessa, ‘Lord of Great Knowledge’.
One of our earliest Irish prose stories tells of the Dagda and his son the Mac Óc, and his mother Boann the goddess of the Boyne. By her union with the Dagda, Boann became the mother of Oengus of the Bruig. The common source of both the Boyne and the Shannon is traditionally in the spring of Segais, the supernatural source of all knowledge, situated in the Land of Promise. It was surrounded by hazel trees, the nuts of which fell into the well producing bubbles of inspiration, or, according to an alternative tradition, were eaten by the salmon of knowledge which dwelt in the spring. Both versions are constantly alluded to in Irish literature as telling the source of wisdom. 
Oengus mac Óc lives in the great síd Bruig na Bóinne, where at night he is visited by visions of a beautiful maiden in his sleep, and he falls into a wasting sickness for love of her. His parents are sent for, and after much enquiry they find that the girl is Caer from Síd Uamain in Connacht, the province ruled in the Heroic Age by Ailill and Medb. Hither comes the Mac Óc and finds Caer and her maidens in the form of white swans wearing silver chains, on Loch Bél Drecon at Crot Cliach in Mag Femin. He calls her to him, and they go to his home in the Bruig. The text of this story is thought to date probably from the eighth century.
One of the most fascinating of the stories of the Underworld is another Connacht tale, Echtra Nerai (‘The Adventure of Nerai’). Here the Underworld is entered through a ‘cave’ (uaim) in the rock near the court of Ailill and Medb at Cruachain in Connacht. As the court are celebrating the feast of Samain, Nera goes outside and cuts down corpse from the gallows who complains of thirst, and after giving him drink Nera replaces him on the gallows. On returning to the court he finds that the síd-hosts have come and burnt it, and left a heap of heads of his people cut off – in fact a typical piece of Celtic raiding.
Nera at once sets off in pursuit, and follows the retreating procession of the síde, who are clearly dead men, for each remarks to his neighbour that there must be a living man in the procession because it has become  heavier. When they enter the síd (cave) of Cruachain the severed heards are displayed as trophies to the king; and the king finds a home and a wife for Nera, and his daily task is to supply the king with firewood.
Then in a vision his wife warns him that at the next Samain the síde will again destroy the court unless he goes and warns the king. He takes wild garlic and primroses and fern to prove that he comes from the Underworld, and he goes to the court of Aillil and Medb and warns then. They destroy the síd, but Nera is left ‘inside and has not come out till now, nor will he come till Doom.’ From the time that he joined the procession of the síde and entered the Underworld he had become one of the dead.
The storytellers of ancient Ireland by whom these tales were handed down spoke of the gods and people of the spirit world as dies síde, or sluag side, ‘the host of the side’. But by the time the stories came to be recorded they had long ago ceased to have any religious or cult significance. The gods are no longer thought of as spirits living unseen in our midst, but as beings of the far past. The scribes who wrote down the stories were Christian monks. To one version of the text of the Táin Bó Cualnge the following colophon is added by a monk or clerk: ‘I who have written out this history, or more properly fiction, do not accept as matter of belief certain things in this history, or rather fiction; for some things are diabolical impositions, some are poetical inventions, some have a semblance of truth, some have not, and some are meant to be the entertainment of fools.’ Although the clerks have lovingly preserved these traditions of an age long past, they have humanized the gods, even sophisticated them. They have deprived them of their original prestige as objects of cult, and relegated them to an artificial setting fitting them to a scheme of pseudo-history which was quite foreign to their origin. We may compare the way in which our Teutonic god Othinn (Woden) is made the ancestor of the earliest Anglo-Saxon kings in our own early records.
The writers of the later legends in Ireland made no distinction between the native Irish gods of the Underworld, the ancient Celtic gods of Gaul who also survived in Irish mythology, and the gods of the supernatural world - Tír Tairngiri, ‘The Land of Promise’; Tír na nÓc, `The Land of the Young’; Mag Mell, ‘The Delightful Plain’. They call all the gods alike by the common name of the Tuatha Dé Danann, ‘Tribes of the goddess Danann’, or simply the Tuatha Dé, ‘The Tribes of the goddess’. The Tuatha Dé Danann imply a goddess Danann, but little is known of her from Irish mythology beyond her name. 
The later Irish writers had good idea that in prehistoric times Ireland had been populated by a series of immigrations and invasions; and they believed that the Goidels were the ruling population of Ireland at the beginning of the historical period. The gods must therefore be earlier. They pictured them as entering Ireland from overseas, just like the later human conquerors of Ireland. The account of the immigration in the Book of Invasions refers to them all as Tuatha Dé Danann. The inhabitants of Ireland whom they found in possession of the land were the Fir Bolg, who are pictured as agriculturalists, in contrast to the Tuatha Dé Danann who possessed magic and all arts and knowledge and handicrafts. The earliest form of the story, however, is the one given by Nennius in the Historia Brittonum, cap. 3.
The traditional Irish account of the invasion of Ireland by the conquering gods represents them as coming from overseas by way of Norway and northern Scotland, led by their druids in a magical mist. Their king was Nuada and they conquered the Fir Bolg, the older inhabitants, by their magical skill and arts, in the first Battle of Moytura, fought near Lough Arrow, Co. Sligo, but Nuada lost an arm in the battle. The Fir Bolg took refuge among the Fomoiri (literally ‘under (-sea) phantoms’) in the Hebrides and Isle of Man. The Tuatha Dé Danann now settled in Ireland as the conquering gods, and made an alliance with the Fomoiri from overseas. The Fomoiri are represented as half human, half monster, with one hand, one leg and three rows of teeth. Their leader Balor had one eye in the middle of his forehead and was grandfather to Lug. Their king, Bres, was related to the Tuatha Dé, and he ruled Ireland as regent after Nuada had lost his arm in the Battle of Moytura. However the exactions of the Fomoiri were intolerable to the people of Ireland. Moreover they were stingy of their victuals, and when the chiefs of the Tuatha Dé went to the feasts of Bres, king of the Fomoiri and regent of Ireland, ‘their knives were not greased by them’ and however often they visited him ‘their breath did not smell of ale’, and he did not patronize their poets or their  horn-blowers, and altogether he behaved very unhandsomely. At last they turned him out. Nuada was reinstated with a fine new silver jointed hand, made for him by the divine physician Dian Cécht and the divine smith Creidne.
We are now on the eve of the greatest of all the stories of the Irish gods. It is very synthetic. The Fomoiri in their turn staged a great invasion, and were defeated by the Irish gods in the second Battle of Moytura. Here the storyteller has brought all the Irish gods together, both native and those from overseas, by a brilliant device in a kind of divine United States and divine Celtic War of Independence, in opposition to the tyrants and oppressors, the Fomoiri from overseas. This skilful device of describing the council of war before the battle has left us a full-length inventory and portrait of all the gods, as well as a view of them in action.
As Nuada has lost an arm he is disqualified from leading the battle. While the gods are in their fortress preparing for the battle, Lug arrives from overseas and claims that he has skill to help. He is not one of the Tuatha Dé. The gate-keeper hesitates to admit him, demanding to know what his skills are; but for every accomplishment that Lug claims, the gate-keeper names a member of the Tuatha Dé who is supreme in this same skill. There is Dian Cecht the physician, who heals the wounded by plunging them in a magic bath-tub, and who had supplied Nuada with a fully jointed all-purpose silver hand when he had lost his own in the battle against the Fir Bolg. Moreover Dian Cecht’s skill was such, as we learn from another story, that when a man lost an eye he could replace it by a cat’s eye. But, as the storyteller remarks, ‘There was advantage and disadvantage to him in that, for by day it was always asleep when it should have been on the alert; and at night it would start at every rustle of the reeds and every squeak of a mouse.’
One of the most important gods assembled for the battle is Goibniu the smith, who makes and repairs the weapons. Another is Luchtine the wright, who makes the shafts for the spears; and there is Creidne who makes the nails. Such is their skill that when Goibniu cast the spearheads so that they stuck in the jamb of the door, Luchtine used to fling the - spear-shafts after them, and it was enough to fasten them, and Creidne used to cast the nails from the jaws of the tongs, and it was enough to drive them in. Goibniu also appears as the smith Gofannon in the medieval Welsh story of Culhwch and Olwen.
Finally Lug claims that he himself possesses all the arts (he is samildánach), and is at once admitted and leads the battle, wearing his famous armour from the Land of Promise where he had been fostered, and winning victory for the gods. 
But the whole grand body of the gods are assembled to help him. His strong champion was Ogma, who is the god of eloquence, and is probably to be identified with the Gaulish god Ogmios.
During the battle Lug was heartening the men of Ireland, ‘that they should fight the battle fervently so that they should not be any longer in bondage. For it was better for them to find death in protecting their fatherland than to bide under bondage and tribute as they had been.’ The words of Lug still ring down through the ages. They might have been spoken yesterday. Then the Mórrígan came and was heartening the Tuatha Dé to fight the battle fiercely and fervently, and the Fomoiri were beaten to the sea.
Now Lug and the Dagda and Ogma pursued the Fomoiri for they had carried off the Dagda’s harper. When they reached the banqueting-hall of the Fomorian king Bres, there hung the harp on the wall. That is the harp on which the Dagda had sounded the melodies, so that they would only sing out by his command; and the harp left the wall and came to him. And he played to them three melodies – the wailing-strain, so that women wept; and the smile-strain, so that their women and children laughed; and the sleep-strain and the host fell asleep. And through that strain the three gods escaped unhurt from the murderous host of the Fomoiri. And after the battle was won the Mórrígan and Bodb proclaimed the battle and the mighty victory which had taken place, to the royal heights of Ireland and to its síd-hosts, and its chief waters and its river mouths; and Bodb described the high deeds which had been done, and prophesied the degeneration of future years.
The story of the god Midir of Brí Léith really links the gods of the síd-mounds with a different group, the gods of rebirth, who do not seem to be primarily associated with the old pre-historic burial mounds, but with journeys overseas. Both groups of gods, however, have their home in the supernatural regions.
The home of Midir is in the Land of Promise and is localized in the síd-mound of Brí Léith, west of Ardagh in Co. Longford. He claims that Étain in her former existence was his wife, but that she has been separated from him by the magic of a jealous rival. When Étain in her later existence becomes the wife of Eochaid, king of Tara, Midir comes to reclaim her. Midir and Eochaid play at chess for high stakes. At first Midir allows Eochaid to win, and Eochaid lays the forfeit on Midir that he and his supernatural host are to build a great causeway across the bog of central Meath. When it is finished Midir again comes to play, and this time he wins, and demands a kiss from Étain as his prize. A month later he returns to claim it. While the king and his court are feasting, and all the entrances are barred, Midir appears in their  midst in all his supernatural beauty and splendour, and carries off ttafn through the smoke-hole in the roof, and they are seen as two birds circling in the sky above the hall.
In this story, or rather cycle of stories, ttain lives in at least three generations, perhaps more, re-born each time, not just living on to old age. In each rebirth she keeps her own name, though her husband’s name differs in every case. First she is Étain wife of the god Midir in the síd-mound. Then she is Étain wife of Eochaid, king of Tara. Then she is reborn as Étain, her own daughter, indistinguishable from herself; for the Irish women were the vehicles by which the dead were reborn in generation after generation. The human husband has no spiritual role.
We shall see that this story of Midir and Étain has a close parallel in the story of the god Manannán mac Lir, the spiritual father of the historical seventh century king Mongán. The only fundamental difference is that Midir belongs to the sid-mounds, the barrows of the dead, while Manannán seems to live by the sea.
The Irish mythological traditions which are distinct in origin from those of the gods of the Underworld, are those of Lug and Manannán, both of whom are directly associated with rebirth. We have seen traces of the ancient Celtic cult of Lug on the Continent, but not of Manannán. In Irish mythology Manannán is king of the Land of Promise, or Mag Mell. According to Irish tradition he had fostered Lug in the Land of Promise and bestowed on him his famous armour – his helmet of invisibility, and his shield, which later Finn mac Umaill had. Welsh prose tradition (the Mabinogi of Manawydan) has preserved his family connexions better than the Irish. Here he is Manawydan, son of Llyr, and brother of Bran the Blessed. One of the earliest Irish stories, The Voyage of Bran pictures them meeting in mid-ocean while Manannán is on his way to Ireland from the Land of Promise; and by his magic he transforms the sea and fish into the flowery plain with its flocks from the Land of Promise. The lyrics in which Manannán sings of the Land of Promise contain some of the loveliest imagery in Irish mythological tradition. And here it must be emphasized that the Land of Promise is sometimes identified as a supernatural region in the síd-mounds, the great barrows of the dead; sometimes as approached over the sea or a lake. It is a land where there is naught but truth; without death or decay, or sadness, or envy, or jealousy, or hate, or gloom, or pride, a land of plenty, of flocks and herds, of the ever-young, of flowers and fruit. It is Mag Mell, ‘the Delightful Plain’, Tir na nÓc, ‘the Land of the Young’; ‘Tír Tairngire’, the ‘Land of Promise’.
The family to which Manannán belonged are not native to any one Celtic country but to the Irish Sea, and all its surrounding coasts, with its nucleus in the Isle of Man. This is, no doubt, why in Irish stories Manannán, like his fosterling Lug, is commonly shown to us as arriving from overseas .
The most interesting gifts of Manannán are his magical powers of creating illusion, and his connexion with the belief in rebirth. Indeed his power of illusion is unlimited. He is a great shape-changer himself, and by this means he is able to control reincarnation, rebirth. He appears to be himself an avatar of Lug. He is a great begetter of children, a soul-conveyor, a psychopompos. He has no normal family life, no local habitation, no direct affinities with the ancient cult centres; but by his sudden appearances and disappearances and his power of shape-changing he can become the father of children of other men’s wives. They are not his own children. He is a supernatural father.
The most astonishing story of Manannán’s fatherhood is the birth of the historical King Mongin († 615) who ruled at Moylinny on Lough Neagh in the north of Ireland, a kingdom known as that of the Cruithni. The story relates that the king, Fiachna Lurgan, goes to Alba (Scotland) to help his ally, Aedáin mac Gabráin (St Columba’s king) against the Saxons. He leaves his wife in the royal rath at Moylinny, where a noble-looking man appears to her and tells her that her husband will be killed in battle next day unless she will consent to bear a son by himself, who will be the famous Mongán. To save her husband’s life the woman consents, and next day this noble-looking man appears in Alba before the armies of Aedáin and Fiachna and vanquishes Fiachna’s opponent. When Fiachna returns home and his wife tells him all that has occurred, Fiachna thanks her for what she has done for him, and the story concludes:
So this Mongán is a son of Manannán mac Lir, though he is called Mongán son of Fiachna. For when he [i.e. Manannán] went from her in the morning he left a quatrain with Mongán’s mother, saying: 
I go home,
The pale pure morning draws near: ManannAn son of Lir
Is the name of him who has come to thee.
But the strange thing is that Mongán inherits the capacities of Manannán. For when he was three nights old Manannán came for him and took him away and fostered him in the Land of Promise, till he was twelve or perhaps sixteen years old. A counter-claim is made in another story that Mongán was Finn mac Cumaill reborn, but he would not let it be known. It was, however, announced publicly in the rath of Moylinny by Caílte, Finn’s foster-son, who came to the rath from the land of the dead. As Mongáin was commonly regarded as the son of Fiachna the Fair, it is just conceivable that the notion that he was a rebirth of Finn may be secondary.
The strangest thing about these stories of Mongán is that he lived in a Christian period. A poem attributed to the poet Mael Muru of Fahan in Donegal claims that Mongin came from ‘the flock-abounding Land of Promise’ to converse with Colum Cille [i.e., Columbanus]; and that he managed to get into heaven by having his head under Colum Cille’s cowl. Is it possible that there had been a heathen reaction among the Cruithni under Fiachna, and that they were re-converted under Mongán, possibly under the influence of Colum Cille? Good relations between Fiachna, king of the Cruithni, and Aedán mac Gabrán, Columba’s king in Irish Dál Riata, which are clearly implied in the story of the conception of Mongán, give some colour to such a suggestion.
The Irish traditional belief in rebirth again takes us back once more to Continental records. Certain Classical authors relate that the Gaulish druids teach that souls do not die, but live again in alio orbe. Gaulish traditions have retained few traces of a belief in rebirth or of the function of a god as a psychopompos, a divine father of children claiming a human father, like Mongán. St Augustine, however, has a curious passage in which he asserts ‘on unimpeachable authority’ that ‘unclean spirits –Silvanos et Panes, popularly called incubi – frequently assail women impudently; and certain daemones, whom the Gauls call Dusii are in the habit of both attempting and effecting this foul act.’ Is it possible that St Augustine has known and naturally misunderstood stories such as we associate with Manannán, and that he is viewing them through the refracted medium of a Christian lens?
It would be hazardous to assume that the cult of Manannán mac Lir has always been confined to the Irish Sea or even that it originated in this area. Early Icelandic and Norse literature has recorded traditions which have close affinities with Manannán and the cult of re-birth and the Land of Promise.
The spiritual role assigned to women in this cult of rebirth is a lofty one. In this phase of Irish mythology the woman, not the man, is the spiritual vehicle who conveys the soul of the dead to rebirth in a later generation. Indeed it may be said that speaking generally the high prestige of women is a feature characteristic of early Celtic civilization and especially of Celtic mythology. We have found the matronae, matres among the oldest figures of Gaulish mythology. In Ireland the native gods, the Tuatha Dé Danann, are thought of as ‘Tribes of the goddess Danann’. The Mórrígan is the ‘great queen’.
History and tradition alike echo the high prestige of women of Celtic mythology. Roman history has recorded no male enemies in Celtic Britain of the stature of Boudicca and Cartimandua. In the Heroic Age of Ireland Medb, Queen of Connacht, is the reigning sovereign. Ailill, her husband, is never more than her consort, and Medb is the greatest personality of any royal line of the Heroic Age.
In Irish and Welsh stories of Celtic Britain the great heroes are taught not only wisdom but also feats of arms by women. In the Irish saga known as ‘The Wooing of Emer’ Cú Chulainn is trained in all warrior feats by two warlike queens — Scáthach, who is also a faith, i.e. ‘a prophetess’, an expert in supernatural wisdom — and Aife. In the Welsh story of Peredur (later Percival) the hero is trained by the nine gwiddonod of Gloucester, who seem to be women of a similar profession. They wear helmets and armour, and they instruct Peredur in chivalry and feats of arms, and supply him with horse and armour. These women also train other young men, and they live with their parents in a settled home, a ‘llys’ or court. The establishment seems to have been of the nature of a military training school.
This high prestige of women is something very old in the British Isles. Among the ancient Picts matrilinear succession was the rule till the ninth century. Bede tells us that even in his own day whenever the  royal succession among the Picts came in question their ruler was chosen by succession from the female line. [….]
[Quotes Ammianus Marcellinus, XV, xii:]
Nearly all the Gauls are of a lofty stature, fair, and of ruddy complexion; terrible from the sternness of their eyes, very quarrelsome, and of great pride and insolence. A whole troop of foreigners would not be able to withstand a single Gaul if he called his wife to his assistance, who is usually very strong, and with blue eyes; especially when, swelling her neck, gnashing her teeth, and brandishing her sallow arms of enormous size, she begins to strike blows mingled with kicks, as if they were so many missiles sent from the string of a catapult. (trans. Yonge.)
It has been suggested above that the Irish gods fall naturally into three main groups, of whom the first, who are also found in Gaul, are possibly the oldest. The second are associated with the prehistoric grave-mounds, and would seem to be chthonic. The third are gods of ‘rebirth’. There is a tendency among leading modem scholars to recognize a fourth class, consisting of certain men and women, heroes and heroines, who appear in Irish literary and historical traditions as human, but who are now generally believed to have been originally gods and goddesses. This relatively recent habit of thought is not confined to Irish scholars. It began among German students of folklore and mythology early last century and has affected mythological studies widely, both ancient Greek and modern Slavonic no less than Teutonic and Celtic. The subject cannot be discussed here, but a few instances may be mentioned of this new category of Irish ‘gods’. This recent tendency forms an interesting contrast to the euhemerizing activities of the early medieval historians who represented the Irish gods as human invaders taking possession of Ireland by force of arms.
It has been thought that Cú Roí mac Dáire, the ruler of Munster in the Táin Bó Cualnge, was a god because of certain magical attributes which he is said to have possessed, and certain ritual functions which he fulfilled in his own person. Yet in the heroic stories he is always represented as a human hero. In a scholarly and detailed discussion Professor Gerard Murphy has argued for a divine origin for Finn mac Umaill, whose milieu is in Leinster and Connacht and who figures in the surviving stories as a human hero. The late Professor O’Rahilly declared categorically that Cormac mac Airt was in reality, not a king but a god. An overwhelming majority of recent Irish scholars insist that Medb, Queen of Connacht in the Táin Bó Cualnge, was a goddess. The evidence is partly philological – her name denoting ‘intoxication’ – partly the long list of husbands attributed to her, partly her ritual marriage. In Irish tradition, however, as in Greek, characters of the Heroic Age are never represented as gods, and literary traditions consistently represent them as human. The tradition may be accepted as it stands.
In an illuminating article Professor Binchy has recently set the ceremonial with which Medb is traditionally invested in a wider context, demonstrating its archaic character and its relationship to royal investiture of other Irish kings, and to kings in other parts of the world which imbued them with divine powers. […]
The Irish gods are always pictured as beautiful in appearance and gloriously dressed. Lug has a golden helmet and golden armour and his shield is famous. An early poem uses the figure ‘Lug of the shield, a fair scál’, i.e. a fair phantom, or spirit, and the late saga of the ‘Fate of the Children of Tuireann’ represents him as wearing the magical armour of his fosterer Manannáin from the Land of Promise. Manannán himself is thus described at his first meeting with Fiachna Find:
He wore a green cloak of one colour, and a brooch of white silver in the cloak over his breast, and a satin shirt next his white skin. A circlet of gold around his hair, and two sandals of gold under his feet.
And again we recall the Gauls as described by Ammianus Marcellinus (XV, xii):
They are all exceedingly careful of cleanliness and neatness, nor in all the country ... could any man or woman, however poor, be seen either ragged or dirty.
On no occasion are we ever privileged to see the gods assembled as a  community in Tír Tairngire or Tír na nÓc; but on more than one occasion we are privileged visitors with a king of Tara who is conducted there on a temporary visit, a kind of mystery. One of the early Irish tales with the title Baile in Scáil tells how the prehistoric king Conn Cétchathach was suddenly enveloped in a magical mist as he was on the royal ramparts of Tara with his three druids and his three poets. A horseman came riding through the mist who took them with him to his house in a rath with a golden tree beside the door. In the house was the god Lug, of great stature and beauty, and there beside a silver kieve full of ale sat a beautiful maiden, the ‘Sovereignty of Ireland’. From a golden vessel she ladled out many drinks for Conn; and with every drink Lug, standing by, named one of Conn’s descendants who would succeed him in the sovereignty, and Conn wrote down their names in Ogam on a piece of wood. Finally the mist dispersed and Conn and his companions found themselves back in Tara. [O’Rahilly, Early Irish History and Mythology, p.283.] This story symbolizes the claim of the Goidelic rulers of Tara to their divine right – possibly also a claim that this divine right is derived from a cult introduced from overseas, and superseding the ancient native gods. A similar adventure – a mystery we may call it – befell Conn's grandson, Cormac mac Airt, but here instead of Lug, the god presiding over the rath in the Land of Promise is Manannán mac Lir. On this occasion Manannán has stolen Cormac's wife and son and daughter and taken them to his home in the Land of Promise; but when he restores them to Cormac he declares:
I make my declaration to thee, O Cormac, that until today neither thy wife nor thy daughter has seen the face of a man since they were taken from thee out of Tara, and that thy son has not seen a woman’s face. Take thy family then,’ says the warrior. ‘I am Manannán mac Lir, king of the Land of Promise, and to see the Land of Promise was the reason I brought thee here.’ [Myles Dillon, Early Irish Literature, 1948, 111f.]
This is a mystery in the Greek sense – a pre-view of the Land of Promise. In a way it is also Manannán's apologia pro vita sua, but it leaves all the important things unsaid. Manannán is the one early Irish god who has never been convincingly humanized by the literary tradition. He is a spiritual being to the last.
It is a strange story, or series of stories. To the modern mind Manannán is the most remote of all the Irish gods from the ideas of our own world. Is it the last outer ripple of Pythagorean continuity of personality transmitted from the late Mediterranean world through Gaul? We know that the Druids are credited with having taught such a philosophy in Gaul; and we have seen that Irish mythology has many links, not only with the mythology of the Celts of Gaul, but also with that of  Wales and even Scotland. It is no isolated mythology, but the fine flower of the whole ancient Celtic world.
Irish mythology demonstrates as clearly as Greek mythology the wide gulf which separates mythology and religion. In both Greek and Irish religions, cults must at some remote period have given rise to the mythology; but the mythologies have travelled far in time, and sometimes in place from their original cult centres. They have reached us, not as religion, but as literary themes. There is neither awe nor reverence for the oldest gods, and gradually, as the gulf widens and religion and belief wanes, a spirit of light humour, even crude horse-play, colours the pictures of these gods. In the second Battle of Moytura, the Dagda, once regarded as Ruad Ro-fhessa, the ‘lord of great knowledge’, has become a grotesque and cumbersome old man, ‘so fat and unwieldy that men laughed when he attempted to move about’. He has a cauldron which holds 80 gallons of milk, and as much meat and fat – whole goats and sheep and swine. All this goes to the making of the Dagda's porridge. His ladle is big enough to hold a man and woman. Yet strangely enough this deterioration does not touch Lug or Manannán. They are in a class apart. Why, one wonders? Their beauty and their dignity never tarnish, nor the splendour of their appearance.
In the great battle which establishes the independence of the gods against the Fomoiri it is Lug, the stranger from across the sea, Lug of all the arts (Samildánach), who leads the gods to victory; even though the Dagda, representative of the older native gods, who had also possessed all the arts and all knowledge, is present. Can we suppose that the cult of rebirth has superseded the ancient cult of the dead in the sid-mounds, and an even older more wide-spread cult – the nature religion of the cult of rivers and springs, so widely attested in Gaul? Perhaps the wide gulf which separates Irish mythology from religious cult is one reason why the Christian monks have felt no inhibition in recording the mythological stories in their books. On the other hand no scruples prevented them from recording the magical practices implied in the mythological stories. The use of the mysterious practice of imposing magical prohibitions known as gessa is constantly referred to, and it was the violation of the personal gessa imposed on Conaire Mór, the prehistoric king of Ireland, that brought about his destruction in the story of the Destruction of Dá Derga’s Hostel. Clairvoyance is widely recognized and its incidence is usually preceded by the verb adciu ‘see’ – i.e. with my eye of inner vision: ‘I see red, I see very red.’ [C. O’Rahilly, ed., Táin Bó Cualgne, p.143.) Charms and incantations are freely used. The technique for obtaining a supernatural vision is recorded verbatim in one Irish text, and is known as Imbas forosnai, ‘Inspiration  which enlightens’, nad the names of other charms are recorded with their appropriate poetical formulae.
Irish mythology is a strange world of imagination. Well might the ancient people of the Mediterranean lands speak of the Celtic peoples, even those of Gaul, as ‘beyond the setting sun, remote from our world’. Yet they are even more remote from the world of the Middle Ages. The Irish gods are neither ‘little people’ nor ‘fairies’, but tall and beautiful and fair; in all their physical strength and power and fairness of countenance, and even dress, they are superior to human men and women. They recall rather the descriptions of the Gauls which we find in Classical writers. There are no withces or devils, no puerile miracles or mere vulgar displays of magical power. The suprenatural and the marvellous are invested with restraint and dignity. No question of guilt, or punishment or judgement in an after life ever disturbs the serenity of what Gerard Murphy has called that ‘strange loveliness’ of Celtic mythology. It is this ‘strange loveliness’ of ‘the otherworld atmosphere which gives its special beauty to the Irish mythological cycle.’ [158; end of chapter.]