Years ago, on Tinakori Road in Wellington, there was a junk shop I would pass on my way to and from work. Inside, the shop was narrow and deep, its dim lighting both concealing layers of dust and casting an appealing lustre upon an eclectic array of second-hand goods. I often stopped to peer through the front window; sometimes, on paydays, I would step inside and browse.

As one who has always found bric-a-brac and antiques shops irresistible, a fair amount of pre-loved stuff has passed through my hands over the years, so it is an odd coincidence that the only two items I ever purchased from the shop on Tinakori Road are still in my possession. The first is a complete set of the short stories of Guy de Maupassant, nine volumes, hardbound. Having carted them around the world and back again, several times, I cannot begin to list the occasions when their presence caused excess baggage complications, let alone explain why I have clung to them so tenaciously. The second item is a squat, cut-crystal bowl, its silver lid engraved with the name 'Carolan'.

That the glass has survived so many journeys and house moves is, in itself, a minor miracle. When I bought the bowl, its inscription seemed merely a pleasing variation on my own name, a more attractive version of the Carol Ann on my birth certificate. At the time, I had no idea of an Irish connection and might not have been interested if I had, for I was a Francophile back then and, as a devotee of Colette, Flaubert, Dumas, and any number of French painters, regarded Paris as the source of all beauty and culture, all things desirable and precious. Since I was barely educated, Ireland, I imagine, might have seemed too bleak and down-at-heel to be of interest, while France's undisputed glamour was more easily accessible.

The crystal bowl travelled with me when, in the 1980s, I took up residence in a small, Celtic country. From the Isle of Man, Ireland could be reached by ferry during the summer months; sometimes, on a particularly clear day, its coastline was even visible from the top of Snaefell, the island's highest point. Irish traditional music seemed to drift across the water on the least breeze, and it was not long before I became aware, for the first time, of Ireland's great composer, the blind harper Turlough O'Carolan. Even so, the move from awareness to appreciation was a gradual process.

In the course of listening to and playing music over many years, I had secretly been conscious of waiting for some indefinable sound to reveal itself to me, perhaps a hint of the divine melody which the planets in our solar system are said to make as they move through their orbits - the so-called music of the spheres - in which we are reckoned to be so immersed as to be deaf to its beauty. At live music gigs, I was always puzzled by people who clung to songs that had been popular in their youth; their constant cries of 'play one we know' made me agitated, since it was precisely the opposite experience I yearned for - to come unexpectedly upon some unique and beautiful sound that would be entirely, divinely new. Sometimes, in the street, I'd overhear a waft of music from an open window or a passing car, and a line, or even a single phrase, would generate a sense of excitement and anticipation. Then, inevitably, the song would take a predictable turn; its melodic line would lose definition, or disintegrate into a disappointing regurgitation of all the popular tunes that had ever issued from a radio.

Then, years after I had resigned myself to never hearing the ultimate melody, it arrived so unobtrusively that it took me a minute or two to realise what I was listening to. At the time, I was already playing a number of O'Carolan compositions, laboriously working my way through both Captain O'Neill's collection of Irish music, as well as some of the ancient pieces collected by Edward Bunting at the Belfast Harp Festival in 1792. I could play an almost acceptable version of O'Carolan's Welcome on my low D whistle, had fallen in love with his Eleanor Plunkett, and the even more exquisite Fanny Poers. But, the internet being the all-powerful tool that it is, there came an evening when a single mouse click launched the sound of Sean Molony, a flautist from East Galway, playing, with great delicacy, O'Carolan's Farewell to Music.

I happened to be sitting quietly, and alone, in front of a decent fire on a winter's evening; creamy church candles burned on the mantelpiece, their glow reflecting in the old, foxed mirror which covers the chimneybreast. As the music drifted up out of my laptop, everything seemed to still, until it felt as if the whole, empty room was listening. By the time the final notes faded, I had, in my amazement, ceased to breathe.

On the website which provided the link, someone had suggested that the tune must have been a gift to the great harper from the daoine sídhe (deena shee), the beings believed to live underground in fairy mounds, or in an invisible world that coexists with the world of humans, literally, the Gods and Goddesses of Ireland. And who is to say that there is not something in this other-worldly connection. Perhaps there is a quality inherent in greatness which has the ability to transcend mortality; Brian Keenan, the Belfast schoolteacher kidnapped by fundamentalist militiamen in Beirut and held hostage by them for four-and-a-half years, maintains that in his prison cell he was visited and sustained by the presence of Turlough O'Carolan who had died centuries earlier.

Farewell To Music is said to be the last piece O'Carolan played before dying. Whether or not it was the last piece he composed, or one that he had written earlier but kept to himself until the moment was right, I believe he saved the best until last. The first thing I love about it is that, although I have listened to it many times, I still cannot hum the complete tune, yet I hear it perfectly inside my head. And when I replay it there, it brings with it a sense of the setting in which it was first revealed to me - the chill calm of the space we call 'the quiet room', with its lit fire, and its old glass flushed by candlelight. In the end, the inside of one's head is the safest place to keep such treasure, captured by the inner ear, to be played at will in the mind's boundless spaces, held close to the heart; once stored there, not a note can be lost or stolen, unless the heart and mind give up, in which case all is lost, anyhow.

The other thing I love about this piece is that Carolan is so very present in it. His wandering, questioning life is all there within the first part of the tune, which seems to move, through harmony, from one pool of shining light, to the next; listening to it, one imagines 17th century Ireland, its handful of blind, itinerant harpers traversing landscapes as wild and beautiful and dark as death. The octave leap at the beginning of the second part, subtly played, has the sound of a spirit lifting up and away, abandoning the earthly struggle, while the little repetitive phrases that follow are a last, gentle insistence on the power of beauty, of art. Finally, in a waterfall of notes, O'Carolan bids farewell to the world, and especially to the music that has been both his life's passion and his source of sustenance.

It is strange the way a single word, a name, engraved upon the silver lid of a crystal bowl, can enter one's life almost casually yet end by becoming an indispensible part of the whole. Now, a day spent without the pleasure of playing or listening to O'Carolan's music would be an empty day, and if his Farewell To Music should be the last sound I hear on earth, there will be no complaint from me. Looking back, the name Carolan seems to have become threaded through my life in a way that has all the appearance of something that was meant from the beginning, or even from before the beginning, a gift from the Gods, indeed.