'The Summer Isles: A Voyage of the Imagination' by Philip Marsden (Granta)

The Summer Isles lie off the far north-west corner of Scotland, a near-uninhabited archipelago of around 20 islands; they are real – so called perhaps because they were used for the summer grazing of sheep – but they also exist in the imagination of Philip Marsden. This is the story of his journey, sailing his 31-foot wooden sloop, Tsambika, from his home in Cornwall across to Dingle harbour, and thence, single-handed, up the western coast along that ruffle of islands that reach into the Atlantic from Ireland to Scotland.

Whatever possessed him? He had never sailed such a distance. The idea of a voyage to the Summer Isles was precious to Marsden. He had, decades ago, spent many happy times on the nearby mainland with his much-loved aunt, by all accounts an unusual and brave woman, who died unexpectedly in what should have been a completely normal mountain ascent in Scotland. They had thought to go together, one day. Therefore, a voyage now was both an inward exploration, inspired in some way by an unfulfilled desire, as well as an outward one.

Marsden, an award-winning author, writer of fiction and non-fiction, brings to his writing a background of anthropology and a broad interest in the myths and stories that abound in not only our own culture but those of other peoples, other countries. In his book, Rising Ground: A Search for the Spirit of Place – mainly sited in Cornwall – it is by walking (a lot of it) that he uncovers how all of us try to achieve a sense of belonging.

In The Summer Isles: A Voyage of the Imagination, the sailing creates its own demands. When asked about the difference between the two, he replied: 'The act of walking, the rhythm of it and the pace of it, affords a certain state of mind. Being at sea is entirely different. It's physical in an entirely different way – and there is the constant awareness that you shouldn't be there, that you're in a hostile environment, that you're vulnerable'.

Certainly the sailing over a period of six months – spring to autumn – was challenging: heavy lumpy seas, loneliness, strong winds, mist and fog, narrow harbours. The rewards, however, were overwhelming: days with the wind abeam, watching waves, dolphins, eye-to-eye with low-flying birds and curious seals, light and colour of the sea, the local bar and infinite choices of whisky. There is plenty here to delight the sailor: the demands of single-handed skippering, the fiddling about with repairs and discussion with other mariners, seamanship, charting the next day's journey, close-calls and successful moorings. All of it is perfectly accessible to the non-sailor, and a sailor's use of boating terminology is easy to follow. It would make a sailor out of any duffer.

At one time, Philip Marsden was going to write a book about the Celts, even going so far as to take a summer course in the Irish language, but thought better of it. Nevertheless, it fed into his early interest in the role of myth, which informs much of the book and which he explores ashore on the islands. 'Myth,' Marsden writes in response to an email interview, 'lies at the very heart of the way we make sense of the world, both as individuals and collectively. It's also something that seems to have been shunted aside in our post-Enlightenment, rationalised world. There are levels of understanding that are reached best through story and analogy and not through analysis. I have always been attracted to places where myth remains important, those areas where stories seep out of the pores of the earth'.

Isn't it strange how often the truth is contained within myths? This is hardly surprising, as we created them to express things about ourselves, to help us order our society, structure beliefs and function as guardians of morality. Myth-making plays multiple roles in human endeavour. Even though the stories may have elements in them that are terrifying, in the experience of telling them their power imbues the teller and the listener. We fear the monsters in our head, and imagine them in myth. Here, on these islands at the edge of the vast ocean, stories come to life, such as that of a mythical island which vanishes but is rediscovered in a magical way, or the metamorphosis of the selkie.

Marsden is a wonderful researcher, poking about in libraries, talking to poets and writers, listening to tales told by island people, aware of the cadence of language and of song. His remarkable prose paints pictures of the land, the often towering cliffs, and of walks through deserted villages and ancient ruins of monasteries that still seem to hold a mystical presence.

The imagination, according to the Longman Dictionary of Contemporary English, has 'the power to convey what is real or could be real, not only outward appearance, but also feelings and thoughts, even when situations and characters are invented'. Whether it is by the story told, the written word, oil on canvas or a prehistoric handprint on a cave wall, there are those whose ability to communicate something of the meaning of existence serves to open a passage to understanding.

For example, Paul Gauguin's enormous painting, Where Do We Come From? What Are We? Where Are We Going?, from the end of the 19th century is a visual voyage of the imagination, painted on an island in the Pacific where he had gone in search of himself, really, as well as the delights of Tahiti. Read from right to left, as the artist intended, it encompasses – enigmatically – the suggestion of birth and childhood, the sea and mountains, companionship, and old age as a monochromatic unknown. He said it was, 'a philosophical work on a theme comparable to that of a Gospel'.

Philip Marsden, too, opens a channel as he explores similar questions to Gauguin, in a different medium, and at the same time he lives the experience while he sails these sometimes treacherous waters, real and imagined. As he says: 'For most of mankind's existence, myth and belief, fear and the imagination have all swirled around in a borderless place where there is no real distinction between them'. Marsden is never afraid to put himself in the picture, to examine his fears and feelings, to give the reader access to his thoughts. He displays curiosity, always taking the time to explore what is local, to garner knowledge and understanding, and pass it on as he interprets it.

The book contains one map for each coast, Ireland and Scotland, detailing the myriad islands, heads, inlets and bays, which makes it easy for the reader to follow the Tsambika on her northward course, sometimes thinking a little anxiously about the next harbour, and then, reading on, feeling relieved as the skipper ties up, takes off his oilskins and goes ashore, heading for the pub. Marsden commented, when asked how the journey had affected him: 'It served to consolidate a truth that I've always found tricky in travelling – that adversity is often revelatory, particularly if confronted in the context of our too comfortable lives'.

The Summer Isles: A Voyage of the Imagination isn't a book that finishes on the final page, when the sails are stowed at the end of the journey, for Marsden has provided a comprehensive bibliography for readers to explore, so that they can continue a voyage of their own imagination. He is generous with his research and there is much here to further knowledge of the myths and stories that inform our lives. The Notes, also, are comprehensive and instructive.

Reading Philip Marsden's book is a shared journey, giving us the nature of the man as well. When asked what surprised him most: 'Goodness – that I managed to do it, I guess'. It is this sense of amazement, delight in discovery, that makes the book such an adventure, in terms of sailing and storytelling.

Philip Marsden will be discussing his book at the Golden Hare Books Festival at The Scottish Gallery, Dundas Street, Edinburgh on 19 October.