There is a high mountain in North Wales called Cader Idris, the chair of the giant Idris, who had a liking for the stars. Although it is a pleasant enough climb of sheep-cropped turf and rocky outcrops by day, the legend goes that to spend a night there will cause you either to die, go mad or become a poet. For Cader is one of those sacred Celtic mountains, hills or barrows which can lead the traveler into bourns from which they may, if unprepared, not return.

The legend of Cader makes evident how thin the line is that separates ecstasy, madness and death in Celtic tradition. Early literature abounds with examples from real life and legend, both of people who have purposefully trained in techniques of ecstasy, and those whom fate has carelessly hurled outside the confines of ordinary consciousness.

Among the highest ranking men in early Ireland were the filidh, a title meaning both ‘poet’ and ‘seer.’ The word itself comes from the root ‘to see,’ for to the Celts, vision and poetry—the rapture of illumination and the inspired voicing of it—were inseparable, the in-breath and out-breath of the ecstatic experience.

As in Eurasian shamanic cultures, the fili was trained in mantic techniques that taught him how to leave his body to ascend to the sky or descend to the underworld to communicate with spirits and the dead, for as Irish scholar Daithi ÒhÒgáin writes, the Irish poet-seer "was a mediator between the supernatural powers and the human race" who displayed many of the traits of the shaman. The ecstatic journeys of the Irish druids and filidh (their functions were often interchangeable) was to gain imbas, roughly translated as "knowledge which enlightens," which was seen as a gift from "the god that kindles fire in the head." The treasures they brought back from these realms might be poetry or prophecy—hidden truths with which they returned to enlighten the tribe. The Christian church put an end to most of these practices, so we have only a few brief but tantalizing glimpses of what must have once constituted a substantial living body of magical knowledge.

In one story, for example, we hear how the great druid Mog Ruith embarks upon ecstatic soul-flight:

Mog Ruith's skin of the hornless, dun-coloured bull was brought to him then and his speckled bird-dress with its winged flying, and his druidic gear besides. And he rose up, in company with the fire, into the air and the heavens..

To enter an inspired trance dressed in bird costume was a common technique of Siberian shamans, for as Mircea Eliade comments:

"Birds are psychopomps. Becoming a bird oneself or being accompanied by a bird indicates the capacity, while still alive, to undertake the ecstatic journey to the sky and the beyond."

But this was only one of the many paths that took druids and filidh through the gates of the Otherworld. They might have traveled by the road of darkness and dreams as described in a 10th century glossary: The poet lies on his back with his hands over his eyes and invokes the spirits to come to him. He stays in this position for three days and nights, guarded by watchers who make sure he doesn’t turn over. This is reminiscent of the classic position for incubatory sleep used in the Asclepian healing temples of Ancient Greece, because it bestows sleep only deep enough for significant dreams to be recalled easily on awakening. A similar technique was in use much later in the Bardic schools of 17th century Scotland where, according to a traveler’s account:

"They [the Bards] shut their Doors and Windows for a Days time, and lie on their backs with a Stone upon their Belly, and Plads about their Heads, and their Eyes being cover'd they pump their Brains for Rhetorical Encomium or Panegyrick; and indeed they furnish such a Stile from this Dark Cell as is understood by very few..."

Special foods or drinks may have been consumed as a means to ecstatic consciousness. The Celts were from Indo-European tradition and most likely had their own version of the mysterious drink of the Vedic people: soma, which was personified as ‘lord of speech’, and as a poet, seer and sage. The word for drunkenness, meisce, signified both "intoxication" and "inspirational ecstasy" in Old Irish, and in later days at least, it was fully expected of any serious Irish poet that he would "add strength to his flights of genius" by downing several jugs prior to composition.

If the juice of the barley kindled "fire in the head" of later poets, in earlier times the brew of inspiration may have been a mead made from hazels, the tree most associated with poetry and magic in the Celtic world. Many early Irish tales describe poets and seers as "gaining the nuts of wisdom" from hazels, while Scottish druids were said to eat the nuts to gain prophetic powers. Hazel mead was said to be a powerful intoxicant, and even to this day there are country-dwellers who believe hazel-nuts to have divinatory powers, and use them in fortune-telling games at Halloween.

Whether the Celts, like the Norse, drank an actual "Mead of Poetry" we will never know, but eating and drinking magical substances is also clearly a metaphor for imbibing the wisdom of the Otherworld. Early Irish literature abounds with tales of heroes who venture into the Otherworld and gain its wisdom by drinking from a wonder-working cup or well. And Welsh bardic literature frequently refers to the "cauldron of inspiration" which contains a mysterious substance called awen, the Welsh equivalent of imbas. Awen literally means "flowing spirit" and is bestowed only by the generosity of Ceridwen, the poets’ muse and mistress of the cauldron. An early poem by a Welsh bard describes his experience of awen when he taps into its powerful force:

The Awen I sing,
From the deep I bring it,
A river while it flows,
I know its extent;
I know when it disappears;
I know when it fills;
I know when it overflows;
I know when it shrinks;
I know what base
There is beneath the sea.

Here the source of awen is in the depths of the sea, a traditional location for the Celtic Otherworld. But it emerges also from the depths of the poet himself, who may have drunk the "intoxicating mead" of the druids. The flowing drink from cauldron or cup sets into motion the flowing spirit from deep within.

One class of Welsh people acted as oracles when filled with awen. In the 12th century, the traveling monk, Giraldus Cambriensis, met these Awenyddion on his journey through Wales. He recounts:

"When you consult them about some problem, they immediately go into a trance and lose control of their senses... They do not answer the question put to them in a logical way. Words stream from their mouths, incoherently and apparently meaningless and lacking any sense at all, but all the same well expressed: and if you listen carefully to what they say you will receive the solution to your problem. When it is all over, they will recover from their trance, as if they were ordinary people waking from a heavy sleep, but you have to give them a good shake before they regain control of themselves... and when they do return to their senses they can remember nothing of what they have said in the interval... They seem to receive this gift of divination through visions which they see in their dreams. Some of them have the impression that honey or sugary milk is being smeared on their mouths; others say that a sheet of paper with words written on it is pressed against their lips..."

As we have seen from the legend of Cader Idris, special places in the landscape were gateways to the Otherworld, and could be entered in a state of trance or sleep. These might be hills or burial-mounds known to be frequented by faeries or ancestral spirits, or sometimes by riversides or on the sea, since water led down into the underworld. The sleeper usually experienced being taken to a magical land by a faery woman who became his mistress and muse, and bestowed the gift of poetry and prophecy upon him. This was most likely to happen when the turning of the year from one season to another left the gates to the Otherworld ajar: at Beltane (May Ist) or Samhain (November 1st,) the threshold times.

Such journeys take the inner traveler out of time, seeming to last for hundreds of years, when only a night has passed. Or as Irish writer James Stephens described it in his retelling of a story about Fionn McCumhaill:

"In truth we do not go to Faery, we become Faery, and in the beating of a pulse we may live for a year or a thousand years. But when we return the memory is quickly clouded, and we seem to have had a dream or even seen a vision, although we have verily been in Faery. It is wonderful, then, that Fionn should have remembered all that happened to him in that wide-spun moment…"

Fionn, who gained imbas by drinking from an Otherworld well or by eating the Salmon of Wisdom according to different accounts, was a true poet-seer who could alter consciousness at will, and bring full remembrance of the ecstatic state back into the everyday world. But there are others in Celtic tradition who were blasted open by forces so strong that ever after the gates to the Otherworld hung loosely on their hinges, swinging wildly in the wind that blew through their minds.

In Ireland these people were known as geilt, probably meaning "wild." Many of them lived in Glenn Bolcan, a valley in County Kerry where "all the lunatics in Ireland" were supposed to be. They lived as wild men, foraging for roots and watercress, in kinship with the animals. Stories about the geilt and their British counterparts often recount how it was the horrors of war caused them to lose their minds.

The most famous of these was Suibhne, once king of Dalriada, who, during a battle was beset with terrifying visions:

"Huge, flickering, horrible aerial phantoms rose up, so that they were in cursed, commingled clouds tormenting him…hovering, fiend-like hosts constantly in motion, shrieking and howling…"

Suibhne rises up out of the battlefield, and flies away to the forest where he proceeds
"to turn his back on mankind, and to herd with deer, run along with the showers, and flee with the birds, and to feast in wildernesses."

The shattering of his mind sentences him to a life of stark alienation from society, but has also unlocked for him the gifts of poetry and seership. Like the druid Mog Ruith, he now is able to fly to the upper world like a bird, and he makes his home in a yew tree dressed in feathers reminiscent of the druid’s cloak. Here God speaks to him, granting him prophetic knowledge "every morning and every evening."

He describes his life in the woods in verse of heartfelt intensity and poignant beauty. When he is told that his wife is sharing his bed with the pretender to his kingdom, he asks her to come and see him, and recites poems to her about their past life – poems that are considered among the most beautiful in Irish literature. But madness is never far away, and periods of exquisite clarity give way to insane visions: headless bodies and bodiless heads, streaming blood, come screaming and leaping towards him, talking about him among themselves and clutching at him till he escapes "into the filmy clouds of the sky."

More than one scholar has compared Suibhne and the geilt to novice shamans whose first entry into ecstatic states is a disorienting and terrifying experience that sends them fleeing into the wilderness. Among some Siberian communities, experienced shamans would teach these sensitives how to control such states and integrate them within their lives for the benefit of the tribe.

Another famous mad poet-seer was Merlin, in early Welsh literature termed "Wyllt," the Wild. Long before he appeared as the wise magician of Arthurian legend, his history was recounted in the 12th century by Geoffrey of Monmouth in his Vita Merlini whose opening lines declare: "I set myself to sing of the madness of the bard of prophecy."

Like Suibhne, Merlin was a king who went mad at the horror of seeing so many of his friends and family slaughtered in a battle. He too becomes "wood-wild" and spends his days wandering through the great forest of Celydon, with a gray wolf by his side. He suffers harsh freezing winters foraging for food, and whenever the occasional traveler chances to catch sight of him, he runs away. His chief refuge is an apple-tree which seems to have magical properties, because when he is in it, none of the search-parties can find him. Here, according to a Welsh text, he composes many prophetic poems, mostly full of grim warnings of the doom that would come upon Wales at the hands of the English, but made personal and touching by each verse being addressed to another beloved companion, a small wild pig:

Oh little piglet,
oh blissful sow,
don’t take your morning nap,
don’t rummage in the undergrowth,…
if you saw
the sheer violence
that I saw,
you wouldn’t sleep in the morning…

For a short while, he recovers his sanity when his brother-in-law, Rodarch, sends a musician to sing and play to him:

"Little by little as he played, he coaxed the madman to put by his wild mood under the sweet spell of the zither."

But when he returns to court with the minstrel and sees the crowds of people waiting to greet him, he "went mad; and once more his derangement filled him with a desire to go off to the forest, and he longed to slip away."

At length his sister Ganieda, realizing that nothing will persuade him to return to the life of the court, builds for him in the forest a house of glass. Here he wanders by night, gazing at the stars and singing the prophesies he learns from them. And unlike Suibhne, who meets with a violent end, Merlin at last recovers his sanity by drinking from a healing spring. In his prayer of thanks to God for this miracle, he rejoices that he is no longer plagued by an ecstasy that gave him no peace:

"I was taken out of my true self, I was as a spirit and knew the history of people long past and could foretell the future. I knew then the secrets of nature, bird flight, star wanderings and the way fish glide. This distressed me and, by a hard law, deprived me of the rest that is natural to the human mind. Now I am myself again, and I feel strong in me that life with which my spirit had always filled my limbs."

For to live in the forest like these "wild men of the woods," is to pay allegiance to the untamed hinterland of consciousness, the rich but dangerous preserves of the mind that lie beyond the well-paved courts of consensus reality. The dense and often trackless medieval forest represents a halfway state between this world and the Otherworld, and Suibhne and Merlin in their trees also live suspended above the ground, not unlike certain early hermits of the Middle East who lived on top of columns to be closer to heaven. The crazy poet-seers literally lived on the very threshold of the Otherworld, but unlike the trained filidh, had no ability to close its gates at will. As Welsh country-people knew for centuries: to spend the night on Cader Idris is to be close to the brilliance of the stars, but also within reach of the cwm annwn, the Hounds of Hell that fly above its crest hunting for souls.