The final sin of John Updike

He married twice, had numerous lovers and four children. When Updike died in 2009 after a short illness, he was pre-eminent among American writers, the one against whom all others were measured. Adam Begley ends his rather magical and utterly compelling and affecting biography by picturing him as a little boy on the floor of the family dining room, "bending his attention to the paper, riding that thin pencil line into a glorious future, fulfilling the towering ambition of his grandest dreams. 'I've remained,' he once said, 'all too true to my youthful self.'"

As Updike also said, he wanted to be "a pretty average person". But there was never, observes Begley, any chance of him being that. "Since childhood," he writes, "he'd been assured he was exceptional, brighter and more talented than the rest. And he surely was." The challenge for his biographer, then, was how to turn such a supposedly ordinary life into the stuff that makes readers want to turn pages.

"One of the last books I reviewed," says Begley, "was a long, long book about Norman Mailer. As I got farther and farther into it, and more and more exciting things happened to Mailer, I had an extreme reaction of jealousy and also irritation, that given this fantastic material the biographer had not done a better job.

"I didn't think Updike's biography was difficult to write because my training is in literary criticism and my inclination is towards literary criticism. What Updike offers to me is much more valuable than derring-do or political campaigns; punching one's colleagues in the faces or biting their ears or stabbing your wife. What he did is write books that drew me to them like a magnet and stories that I could turn to.

"And then there is the extraordinary story of how he transmuted the minutiae of his life, which every time he did it, it astonished me afresh. What happened is that whenever I felt my forward momentum was flagging I would turn to what he was writing at the time and I would be lifted up, sustained, and a combination of thrilled and excited by discovering the meaning of what he was writing throughout his life. And also, grateful to him for so consistently having turned out fiction and non-fiction and poetry that repaid close attention."

Like his subject, Begley is American. For the past 17 years, though, he has been living in a small market town in England with his English wife which he pitches in estate-agent speak as "a little paradise on earth", and which he has no desire to leave, "for many reasons". It sounds very Updikean. "Yes," says Begley, his accent that of his birthplace, "but I don't sleep with my friends' wives. Or at least not all of them."

Updike and he share some history. His father and Updike were classmates in college and later, when each of them married, lived near one another and were on friendly terms. Once, when Begley was an infant, Updike dropped by the house and entertained his future biographer by taking three oranges from a bowl and juggling them. Family legend has it that this was the first time Begley laughed until it hurt. He first met Updike as an adult in 1983, when he spent a day and a half in his wake, "playing Boswell". Thereafter, they spoke on the phone perhaps a dozen times and had two extended tete-a-tetes.

"I was amazed and delighted by his gracious, marketable self," Begley writes. "He wanted to let you know he was perfectly aware of the falsity of the situation, and perfectly prepared to be amused by it, for the moment. He wanted to let you know his real self was elsewhere."

As a teenager, Updike wanted to be an artist but, prompted by his mother, herself a published author, he was directed towards writing. At the New Yorker, he rattled off short pieces for that section of the magazine known as the Talk Of The Town, which gave him licence to rove the city. Even at that early stage in his career, writers of greater seniority recognised his talent and precocity. He married young and soon had children. It would have been easy to be sucked into the social life of the city and succumb to being feted, but Updike realised his terrain was not concrete canyons and crowded subways but that part of America where the pace of life was slower and interruptions fewer and more manageable.

Not, of course, that there weren't temptations. In Massachusetts, Updike's Wessex, where in the 1960s adultery was almost taken for granted, he was serially unfaithful. In his novel Couples, Ipswich, the town in which he lived, became Tarbox, a hotbed of wife-swapping and sexual shenanigans.

Set at the time of the Kennedy assassination, it showed America at its most decadent and, some argued, its most degenerate. On the day the president is shot the five couples at the core of the novel barely pause to register their grief before deciding to proceed with a dinner party as planned. It was a mirror of reality. As Updike later explained, "We didn't know what gesture to make, so we made none."

Begley does not ignore Updike's libidinousness but neither does he dwell on it. Names are mentioned when absolutely necessary and he never goes out of his way to identify or embarrass all the women with whom the writer might have had a liaison. In that regard his is a sympathetic book, even with regard to Updike's attitude to those closest to him.

"I came to Updike with guarded affection," he says, "and I came out with greater admiration than I went in with. And I still have some reservations about some aspects of his character. In the end, I am happy he was willing to sacrifice the happiness of people around him for his art because I am selfish and I love his art. Part of me thinks art is more important than people's transitory personal happiness. But if you turn a blind eye to what he did, and what he failed to do as a parent and a husband, then you are misjudging him as a character ... I have been accused of being a little bit soft on him. I don't know if I was. I just wrote it the way I saw it."

The character who emerges from Begley's book is complex and fascinating and, to a degree, elusive. There was, for example, the public figure, who could turn on the charm as one might a light. He was studiedly polite and played the part of literary gent almost to the point of parody. By nature, Updike was also careful and cautious and conservative. For much of his life, moreover, he had a stammer and was plagued with psoriasis. And, having grown up as a single child in a family that always had to count pennies, he could never fall back on privilege. He had to plough his own furrow.

But there was also another side to him, observes Begley, that of the daredevil and the practical joker. As a teenager, he would woo his pals with stunts, jumping on the running board of his parents' old black Buick and steering it downhill through the open window. He was prone to tomfoolery, as if determined to draw attention to himself. He liked to leap over parking meters and would throw himself downstairs as if he were part of a slapstick act. "So there is that contradiction in him," says Begley, "that is elemental in him and that biographers like and which they pretend they can explain, but can't."

What is clear is Updike's passage from that of unknown writer to revered bestseller was as smooth as is imaginable. He suffered no privations and spent no hungry hours in damp garrets. Nor did he ever really know what it felt like to be rejected or suffer from writer's block. From the outset, he was - and felt - blessed. He began by writing poems and that is how he signed off. In between, his stories and novels offer as vivid and as valid a portrait of American life in the second half of the 20th century as it is possible to find.

"Updike had the most amazingly easy ride of any major American author of his time," acknowledges Begley, "and that in itself has created some resentment. There is a suspicion that if he didn't sweat and didn't struggle and overcome obstacles in his early youth then it can't really be art. This is clearly to me a hangover from romantic assumptions about the nature of solitary poetic genius that I am not sure I believe.

"One of the things that energised me when writing this biography is the virtue of hard work. And that if you have a talent you must apply to it with concerted effort. That is how you get an oeuvre of the kind Updike produced. It is not by getting drunk or stabbing your wife."

It is a salutary reminder of what writing great literature demands of its creator. Influenced by Proust and Henry Green, Updike was first and foremost a stylist. His sentences roll across the page like tumbleweed down Tombstone's main street. But style is increasingly of interest only to a limited few. Whether it will be enough to keep Updike's flame alive is uncertain.

Adam Begley, who has read more of his work than almost anyone else, believes his short stories "are unassailably part of the canon" and that at least half a dozen of his novels - including the Rabbit tetralogy - will remain in print. Then there are the poems, a number of which will surely survive the ravages of time.

It is not a bad legacy, and better than most. Long before he died in January 2009, Updike had given up all but one of his vices - smoking, drinking, sleeping around. "It's true, his last sin was writing," says Adam Begley. "This compulsion to take other people's lives and use them for his own ends. Other than that, he had given up naughtiness."

Adam Begley is at the Edinburgh International Book Festival on August 19. His book, Updike, is published by Harper at £25