Roger Deakin's Waterlog was the literary gem of 1999. The conceit was simple: the author set out from his moated farmhouse in Suffolk to swim across Britain in a succession of streams, rivers, ponds, fens, tarns, lochs, pools - natural and man-made - and, of course, the sea itself. Emulating the protagonist of John Cheever's classic short story, "The Swimmer", Deakin created a special kind of literary classic, at once a travelogue, a discourse on natural history and an investigation into the culture and mores of our island people.
I read a lot of books - but Waterlog was one of my favourite kind, not only because of its subject matter, but also because of its methodology: the pitting of the individual psyche against the tumult of being itself. I didn't know Deakin - who, as well as a writer, was a film-maker, broadcaster and environmentalist - but like many other fans of the book, I felt as if I did. His was a witty sensibility, as happily afloat on the whirlpools of mutable time as he was on the sinuous rills of his beloved water.
Few books make you change your habits; this one changed mine, and those of several of my friends who read it. We became, if not as accomplished wild-water swimmers as its author, certainly passionate converts, ever ready to plunge into the turbid brown Avon - even in icy May - or scull out into the choppy Channel. Deakin's basic message - that swimming in wild water makes you happier and better adjusted, both to your habitat and its inhabitants - was confirmed with every scamper over the pebbles, each heart-stopping plunge into the elemental bouleversement.
Then, last year, the news came that Deakin had died, aged 63, of a brain tumour. All that vigorous, onrushing motion stilled by the scuttling crab - it didn't seem right. But he had managed to finish, in the last few days of his life, the manuscript of a second book: Wildwood.
It's inevitable that a book as keenly anticipated as this one should prove, if not exactly disappointing, somehow disorienting. I wanted the same experience as Waterlog - but Deakin provided a different form of immersion. Gone is the straightforward trajectory through water and in its place comes a path as convoluted and knotty as its subject matter. Gone, too, is the lightness of writing about the natural world that made it possible for a city dweller such as myself, who doesn't know his ash from his elder, to make believe that he's happily feral.
Despite growing up in Watford, Deakin became an enthusiastic naturalist when he was a schoolboy. On botanising trips to the New Forest organised by his teacher, the eminent entomologist Barry Goater, Deakin immersed himself in the close study of flora and fauna. In Wildwood he returns to Dorset, and in Goater's company walks the same paths, cataloguing sylvan diversity. Deakin quotes the 19th-century agriculturist William Cobbett approvingly: "What are these deer for?" He lauds Cobbett for his practicality and lack of cant, yet so many would-be modern Cobbetts are distinguished by their capacity for the self-righteous homily. Deakin never stoops to that. Although a committed environmentalist - he was a founding trustee of the arts and environmental pressure group Common Ground - he didn't build wooden tubs in order to thump them. His passion for the natural world and anger at its degradation are expressed through the praxis of conviction: he is the antithesis of a high-profile eco-warrior, hopping between jets on his way to the next earth summit.
Long time resident in Suffolk, where he took over a dilapidated, cruck-built farmhouse and reconstructed it himself, Deakin managed his own smallholding, swam in its moat, turned wooden bowls on his lathe and - in homage to his friend, the wood-sculptor David Nash - created an Aboriginal-style wiltja out of living ash trees. Some of the most moving passages in Wildwood concern this philosophy, woven out of the living wood of Deakin's copses and hedges. Sitting at his desk, sharpening a wooden pencil and observing the quotidian - yet special - place he had created, Deakin allows his mind to take flight through time and space, brachiating through a forest of fact and fancy. From the walnut burr veneers of which Jaguar dashboards are made (and in this section Deakin, a motorist himself, is notably deft) to the propellers of First World War aircraft, he locates wood as an ur-substance: building material, art object and artefact; a furniture of the world that, like the ridge pole of a tent, supports the canopy of effulgent life.
His obituarist in the Guardian, Ken Worpole, located the two poles of Deakin's life-work as the anarchism of Colin Ward and the Anglicanism of Ronald Blythe - both Suffolk neighbours. From childhood holidays in this neck of the woods, I feel I have some affinity with Deakin's milieu, the hippy proto-greens of Barsham Faire and "Coypu Comix" in the mid-1970s, who were, in their turn, the lineal descendants of the Woodcraft Folk and, before them, the Men of the Trees. This is a Janus-faced tradition, politically, with one visage set woodenly on the sacred groves of the past, the other on the more pliant saplings of futurity. It's a furrow perhaps best ploughed in Patrick Wright's masterful history of 20th-century English environmentalism, The Village that Died for England.
Of course, unlike Deakin, I've lived out my life cocooned by synthetics rather than minutely observing the creation of cocoons. Part of what makes Wildwood a bewildering read for the non-naturalist is Deakin's complete absorption in his chosen subject: he augurs his way into his material, following the narrative grain from the ethnology of ravens to the construction of writing desks. In truth, I found him weakest as an art critic; and although his writing on David Nash in Wales, Mary Newcomb in Suffolk and John Wolseley in northern New South Wales is undoubtedly impassioned, I'm not sure his exploration of the allusiveness of man-made artworks matches the precision with which he describes natural processes.
Deakin supplely weaves withies of observation together, covering journeys to the Spanish Pyrenees in search of the rare Albères cattle that browse the cork oaks; a wintry trek through the Bieszczady woods of the Polish-Ukrainian border; a study of the human diversity of the Pilliga forest of northern New South Wales; a stroll through the chestnut groves of the Hérault and the olive ones of Lesbos. The most spectacular of his travels is a trip through Kazakhstan and Kyrgyzstan, where he encounters local arboriculturists who harvest amazing wild walnut forests, and visits the ancestral home of the apple.
Yet, enthralling as these travels are, it's back home in England that Deakin's writing takes flight, especially in his descriptions of his own Suffolk homeland. His intimate accounts of hedging, coppicing, grafting, pruning, and eventually planning and turning his beloved wood, may have made me feel inferior, but I experienced atavistic stirrings and desired to go tree climbing once more.
Even now, sitting in stony Stockwell, south London, with his posthumous gift on my lap, I'm moved to consider what exactly is the benefit of Deakin's brand of raised, woody consciousness? Not all of us can live the life of praxis that he did, yet on finishing Wildwood I found myself thinking more concretely about the trees - and wood - in my life than heretofore. Even if it's only the carbonised briar in my tobacco pipe, the planed pine of my custom-carpentered desk, the cedarwood in my cigar humidor, Wildwood has provoked me. Perhaps this year, under Deakin's influence, I will finally learn to tell my ash from my elder.
Will Self's latest novel, "The Book of Dave", is published by Penguin