PrologueWhen I first see her she is as still as a found stone, in an ancient and hidden place. She stands out, a quiet caller of the eye - her markings blend in so delicately in this place, against the grasses and the thistle, the sand that marks the Atlantic Ocean from the land. I am at An tSrúibh - Shroove Beach - completely alone, miles across the border from my home in Derry, when we cross one another''s path. She looks so calm, unstirring in spite of the winds that now set the tall grasses on the beach to dance. She is so beautiful - I may even call her celestial - that I almost feel I have no right to be here. In this moment, in this place, with this graceful wonder, what part can I play in her story, in the narrative of this ethereal offering of a creature? I begin to feel that I am not, in fact, even ''seeing'' her. It is more an act of witness. There is so little action in the small part I play on this near-winter morning, at a part of the Inishowen Peninsula where Lough Foyle meets the wild Atlantic, at the edge-land of Donegal, in one of the most northerly places on the island of Ireland.

We have found ourselves in a state of turmoil here, in the North of Ireland, and all the other parts that make up the United Kingdom are caught up in the same storm. It is November 2019, and next month the first Christmas Election in decades will take place. The air has been charged for many months with worry and confusion but none of that seems real, here, amidst such silent serenity. She dances. She is the centre of it all, the still point on the map, a heavenly and delicate thing, too sacred for words. I am only the beholder, here, and I am drinking it all in. I bathe in her silent, gossamer grace. I watch her for what feels like a hundred years - one hundred years and this one, solitary day.

The winter sun is high enough above the lighthouse to make the reeds double on themselves. Their silhouettes now join her in shadow play; they seem as if they are weaving themselves together and dancing in time with her. I am on my own, on the outside, looking in at the reeds and the moth; as if I am on the other side of an ice-sculpted lake or a mirror. They are right here beside me yet they feel so completely out of reach. I tiptoe around the edges, and I feel myself outside time, as well as place. Now I am in both and in neither all at once. I gratefully wait on the threshold, holding my breath as the reeds dance, grass goddesses on the hushed dunes, beside an ethereal, exquisite leamhan . A winter moth, in a weightless, willowy place.

I begin to dry myself. The water today was icy and the sea''s waves tall and white as snow, like mountains she had given birth to overnight. I am shivering, now, violently, on the wet November sand, but I feel like I have been made new, somehow. There is almost full silence. All that undoes it are the soft sounds of the dreoilín - a wren - and the water as it ebbs and flows out at the horizon. Then, all out of nowhere a deep, melancholy cry rings out over the dunes. A call that speaks of wildness, of solitude, of survival and unimaginable beauty. Twelve curlews are in flight in the sky above my head, calling out over the edges of the eastern coast of the Inishowen Peninsula.

They are the same colour as the dunes, the grasses and the other winged creature on the beach, that almost otherworldly moth. Their call is haunting - a siren song written long ago, and it drags me with it: out of myself, and back in again - out and in, like a wing-beat, or ebbing breath. They have long held a place in our history as a marker, these folkloric birds: of the past, of the cruel and melancholy passing of time with all its irrevocable changes. The curlew''s cry has shape-shifted into mournful lament - an elegy for all that is lost. For centuries, it has been taken as a sign of unbidden sorrow yet to come; the cries of those whistlers is a sound steeped in foreboding. Those creatures of coast, marsh and bog carrying disaster and grief, carefully, in the fine curves of their bills. This beach on which I stand, shivering and silvered by the salt of the Atlantic Ocean, is a perfect place for them - open, empty and desolate, at first glance. This beach - Shroove, Stroove, or Strove, depending on where you grew up - has a quality to it, a stillness, which lets me almost float away.

It allows me to see things differently. It is as if the veil between worlds has become as thin as moth-wing. The lines that are normally drawn for and by us - between here and there, between now and then - seem as though they have been washed away, on some days. I shiver again, pull my arms in around the curve of my body and wonder if it is the sea that has made ghosts of what we think we know here, in this wee nook at this most northerly tip on this divided, broken island. This shipping lane has been used for hundreds of years by ships carrying Irish emigrants to land far from where I stand - England, America, Australia, Canada. This rugged coastline has not only transported people, it has stolen them, too. She is a hungry sea, this one I am drawn to - pulled towards, tidally. She has claimed hundreds of ships, taken innumerable lives; the body of water in front of me holds a story of deepest loss within her belly.

Now, through the lifting mist, Ballycastle - in the north of Ireland - comes into view, only just. One moment the coastline is there, and then it isn''t. It is a fleeting and flighty thing today, the outline of that other place across the sea - and border - from me. There are times at which, under certain conditions, Scotland can be seen from where I am standing, as clearly as if it were right there in front of you, as if you could hold it tenderly inside your own salty, shaky hands. Today is not one of those days. The only land that I can see from here is still in Ireland, across an invisible border, parts of both its sides are held in place by the ancient, changeable and wild Atlantic in front of me. This border - unseen, hand-drawn by man, and for him alone, too - has been the thread that has run through my life. A ghost vein on the map of my insides, it is a line that is political, physical, economical and geographical; yet it is a line I have never once set eyes upon.

This invisible line - a border that skims the water I have just emerged from, as though it were a dragonfly - has been the cause of such sorrow and suffering, such trauma and loss, that I ran from its curves and coursing flow at the very first chance I got. I was half the age I am now when I left my hometown. The year that I moved back, the UK voted to leave the EU. Despite the words about unity, solidarity and strength in togetherness, lots of people decided they wanted to choose a different path. Derry - my border town in the north-west of Ireland - known for being the place ''the Troubles'' began, voted to remain. There is a very particular type of wisdom that is born out of witnessing unimaginable cruelty, out of the experience of dark, harrowing sorrow. I remember standing on this same beach just after that vote and weeping, memories surging through my insides like hidden tributaries. No more, no more, no more - we have all had enough already, enough for many lifetimes.

That border has become a thread in the lives of so many more people between that day in 2016 and this one, three and a half years later. The fog has lifted a little; to the right of me, its silky grey veil is still laid too low to allow the outline of Scotland to come into view. Now, just below the lighthouse, the crotach - the curlews - grace the middle part of the sky again. They are heading round the curve of the bay towards Greencastle, maybe even onwards yet. Maybe they are flying away from here, where Lough Foyle floods into the Atlantic Ocean, to follow the flow of the river across the border and into the North. Or maybe they will turn the other way, chart a path over fossil-traced bog-land, above gorse and ceannbhán - bog-cotton - where butterflies and moths have left fragments of their tissue wings. Maybe today they will choose to fly above estuary and stream, over the mountains of the Donegal Gaeltacht, their cries blending together with words in the native tongue of those they fly above, in the South. They nest all over this land, those of them that are left, on both sides of the border.

The season is turning; I felt it so fully in the water today. November''s full moon marks the birth of a new Celtic year, at the same time as symbolising an end, the death of the old year. It is known as the mourning moon in Pagan tradition. In many cultures, this full moon is intimately connected with death and loss, on both a literal and symbolic level. Some folk call it the snow or fog moon, and I can both feel and see why, today, as I shiver beneath sea fog that hides the sun away. There is a pale yellow-grey hue to it, and a softness that could easily bring the snow. My ancestors knew it as the reed moon. I watch as the giolcach - the reeds - move about in the icy breeze, and I imagine my ancestors watching too, from a place, like the full moon, that I cannot see.

To the Druids and the Celts, almost everything in the natural world was tied in some way to the greater being - the spirit - of the earth. For our ancestors, our role in it all as guardians was one of unshakeable magnitude. In Ogham - ancient writing on stone - the letters are named for trees, an alphabet of arboreal forms, only some of which are still known to us. The etymology of the word ''ogham'' is not fully known but it may have roots in the Irish og úaim - ''point-seam'' - the trace left over by the point of a sharp weapon, the midway mark. The stones on which the writing.