Biography: 'Hark to those thunderous volleys that stun high heaven", James Clarence Mangan wrote in his 1849 poem 'Denmark after the Battle of Copenhagen'.
Not many people outside Copenhagen may have felt the tremors, but that same year philosopher Søren Aabye Kierkegaard published no fewer than four books, capping a decade of profligate creativity. He was already the author of such classic works as Either/Or, Fear and Trembling, The Concept of Anxiety and Concluding Unscientific Postscript, yet by the time of his death six years later he was probably best known to the public as the victim of a campaign of vilification by the satirical newspaper the Corsair, while an unseemly squabble literally over his dead body at his funeral further confirmed Kierkegaard's disreputable standing.
He had wished his gravestone to read simply "That individual", and it took long decades before "that individual" was vindicated as one of the greatest of 19th-century thinkers, rivalled only by Nietzsche and Marx as a prophet of philosophical modernity.
Kierkegaard was born in Copenhagen in 1813, one of seven children. When five of these died before adulthood Kierkegaard's father became convinced he was suffering retribution for having once cursed God as a boy. The same crippling sense of guilt resonates through his son's work, as suggested by the title of one of his sermons, on 'The Edification that Lies in the Thought That in Relation to God We Are Always in the Wrong'. Kierkegaard knew all about feeling in the wrong after the defining event of his life, when in 1841 he broke off his engagement with the teenaged Regine Olsen. Out of his deep sense of failure came the famous 'Diary of a Seducer' in Either/Or, and a resolve to commit himself to his writing as an act of religious atonement.
And so his life might have continued, but for the Corsair fiasco. Kierkegaard had only himself to blame for this, going out of his way to insult that paper's well-disposed editor, and attracting such unrelenting bad press that his beloved rambles through the streets of Copenhagen became impossible. He fought back doggedly, and became obsessed with attacking the hypocrisy of the Danish state church. By now he had succeeded in achieving the pariah status which he perhaps had been looking for all along. No one familiar with Gillray or Steve Bell's cartoons will find the Corsair's depictions of Kierkegaard as a hunchbacked village idiot all that scathing, but the photographs reproduced here of his stern-eyed patriarchal adversaries suggest this was not a culture inclined to take impropriety lightly. Kierkegaard knew how to dish it out too, snarling at the press as the "government's filth machine" and calling the Bishop of Zealand a "glob of snot".
But a perverse irony lay in wait for Kierkegaard. The more extreme his polemic became, the more the Christianity he defended came to seem above and beyond not just his doltish enemies but everyone else too. As he wrote in his journals: "In the beginning there was no Christian at all. Then everyone became a Christian - and that's why once again there is no Christian. That was the end. Now we are at the beginning again." Or as Nietzsche wrote 40 years later: "There has only been one Christian, and he died on the cross". Extreme theism and atheism bizarrely coincide. Worn out by these quixotic jousts, Kierkegaard collapsed in the street in 1855, and died shortly afterwards.
This is an epic book, and truly a biography of the work as well as the man. Garff is excellent on the mixture of grandeur and provincialism that was 19th-century Copenhagen. He gives us the whole hinterland of Kierkegaard's intellectual life, and its supporting cast of friends and enemies. But above all he gives us a portrait of a writer, completing the project he began with his lavishly detailed earlier study Written Images: Søren Kierkegaard's Journals, Notebooks, Booklets, Sheets, Scraps, and Slips of Paper.
Kierkegaard is one of the great stylists among modern thinkers, but as with Wittgenstein or Simone Weil, to enjoy him for mere fine writing is really not to read him at all. The hall of mirrors of Kierkegaard's personae might make him appear a precursor of postmodernism, with its delight in game-playing and disbelief in the unitary individual, but his dogmatic edge is entirely at odds with our easy-going contemporary scepticism. He is an unrepentant absolutist, "one of those unmoved souls in whom there is a perpetual 'Last Day', a perpetual trumpeting and coming up for judgment", as Yeats said of Synge.
Even so, he is by far the funniest of the great philosophers. With his combination of inspissated Nordic gloom and impish humour he can read like a cross between Ingmar Bergman and Woody Allen; no wonder Woody puts him on the New York Knicks' basketball team in Annie Hall ("Kierkegaard . . . passes to Nietzsche . . . fast break to Kafka"). The resemblance to his Irish contemporary, Mangan, is striking (not that Kierkegaard would have heard of Mangan): the romantic disappointment, the hectic productivity, the lifelong residence in one small city, the eccentric dress, and the love of promenading, umbrellas, coffee and, above all, mayhem-wreaking pseudonyms.
One of these is a would-be author, ABCDEF Goodhope, who attempts to woo subscribers for his unpublished book by offering to visit their houses, give them a shave, brush their clothes and polish their boots. We could hardly be closer to the spirit of the sage of Fishamble Street.
The 20th century is dotted with improbable loners - Cavafy in Alexandria, Pessoa in Lisbon (another connoisseur of the heteronym), Kafka in Prague - whose apparently marginal lives became central to our conception of modernist writing. Keeping solitary watch over his own corner of Europe, Kierkegaard stands behind all these writers as both patron and exemplar. To understand him is to understand our modernity and ourselves. This book is a marvellous achievement.
David Wheatley is a poet and critic