Like a medieval holy man, or modern hippie, Robert Macfarlane sets out for the remote parts of the northern and western British isles, sea-sprayed islands, craggy mountains and great bog plains. He wants to experience wildness. There is not an icy pool he will not plunge into or tree he would not climb. He picks up shards of roughened granite and smooth flints and turns them in his hand. He says: “We have in many ways forgotten what the world feels like.” A Cambridge academic, who has previously written about men's fascination with mountains, Mr Macfarlane does not forsake civilization. On the two occasions that the elements threaten him—on the summit of Scotland's northernmost mountain and at the foot of a remote Hebridean climb—he briskly retreats. In scholarly fashion, his urge is to map, to classify and to name. He presents his travels as a “story map” (medieval forebear of the Ordnance Survey grid map) connected by incident and historical anecdote. As a narrative ruse , it is a little too cute. As, indeed, is Mr . Macfarlane's beautifully worked but sometimes monotonous prose. Nonetheless, this is indeed a good book, replete with wonderful tales. Like that of Schiehallion: a Scottish mountain so resembling an isosceles triangle that an 18th-century mapmaker used its measurements to estimate the density of the Earth. Or of W.H. Murray, a chronicler of Scotland's hills, who kept his sanity in a Nazi prison-camp by describing them on toilet paper. Or, perhaps the strangest, a metaphoric connection that Mr Macfarlane makes between the Holloways of Dorset—lanes deep-trodden into its yellow sandstone—and the 16th-century recusant Catholics who skulked in the county. Predictably, Mr Macfarlane comes to realize that every place in Britain's crowded archipelago is swamped in human history. Its empty margins have been cleansed of large populations: western Ireland by 19th-century famine and emigration; northern Scotland by 19th-century emigration and evictions . He adjusts his idea of wildness. It is not nature unsullied, but nature itself: “the sheer force of ongoing organic existence, vigorous and chaotic.” Like many English poets, he comes to find “visions in ditches”. A lichen -encrusted hawthorn trunk appears as a “shaggy centaur 's leg”. But British nature is everywhere depleted. Of 6,000 acres (2,400 hectares) of surface limestone pavement, 200 remain undefaced . Since the second world war, a quarter of a million miles (about 400,000km) of hedgerows have been erased; another 2,000 miles disappear each year. As the climate warms, more terrible change is threatened. Scottish sea-bird colonies are already starving, as their prey heads north for colder waters. Every year, almost an acre of Essex salt-marsh, a precious flood-defense, is lost to the rising seas. England's last great beech woods, Mr Macfarlane worries, may wither in his lifetime: 50-year-old trees are showing signs of a decline typically found in trees three times as old. There may be no hope of arresting this change. Yet Mr Macfarlane consoles himself with the thought that nature, endlessly changing, will not all die. The beech woods, too, will move north. And when people are gone, nature will remain. “The wild prefaced us, and it will outlive us.” It is a depressing hope.