DEATH IS the one sure-fire certainty in life. No bookie will give you odds on escaping it. It is, as Julian Barnes intimates, the one thing we can rely on; it is 100% guaranteed. But is it something, or nothing, to be frightened of? Is death it? Is that all there is, a full-stop, a whistle blowing the end of the game? Or is there more? In a word, can we expect or at least hope for an afterlife and a refutation of that glib slogan: "Life is not a rehearsal"?

Barnes is preoccupied by death. If most men think about sex more often than what they're going to have for supper, then he is similarly consumed with thoughts of death. Moreover, he fears death, which is harder to admit than some think. The world, as he sees it, is divided not simply into those who fear death and those who don't. He offers four categories. There are those, for example, who do not fear death because they have faith, and those who do not fear death despite having no faith. Then there are those who have faith but "cannot rid themselves of the old, visceral, rational fear". And then, Barnes adds, there are those, such as himself, who find themselves paddleless up shit creek, who fear death and have no faith.

One suspects there are more categories than this, faith being something that is not black and white. What of those, such as myself, who have some faith and don't know whether they fear death or are sanguine about its inevitability? What many hate most about death is not dying but the business of dying. We see ourselves incapacitated, incontinent, incomprehensible, life's pleasure sucked out of us, our bodies as useless as cars on a scrapheap. Most of us, one suspects, given the choice, would take the death which the novelist Mary Wesley hoped to have, and which her family was famed for: here one minute and gone the next. But, as Barnes reports, things did not work out for her as planned. Instead, she died of cancer, slowly and stoically, as no doubt many of us will.

Nothing To Be Frightened Of is a discursive and book-length essay which Barnes's fans will adore. In part, it is autobiographical, but not in the manner, say, of Blake Morrison's And When Did You Last See Your Father?, though there are similarities. For a start, the milieu he evokes - middle-class, suburban, quotidian, post-war, Any Questions on the wireless, The Lone Ranger on television - is much the same. Barnes's father taught French and his two sons inherited his francophilia. Neither sibling's relationship with their parents was close; affectionate in the reserved English sense perhaps best describes how they felt towards one another. This was not a family given to comforting hugs and expressions of love. Barnes's elder brother became a philosopher and the competitive edge between the two endures. When Barnes told his brother that he didn't believe in God, but misses him nonetheless, his brother replied with one word: "soppy". The book proceeds from this unlikely overture: Barnes the novelist probing and imprecise and impressionistic; Barnes the philosopher reacting laconically, as if tutoring a bright but woolly student. Of the two, the former is the more appealing.

Barnes is 62 and at that age - the seventh decade, long past the point where one can expect to live as long again - when to begin a book is an expression of hope. Of course, we can die at any moment. None of us knows when. But there comes a point in all our lives when thoughts of death cannot be ignored, when it is ever present. "A sense of death," writes Barnes, "is like a sense of humour. We all think the one we've got - or haven't got - is just about right, and appropriate to the proper understanding of life. It's everyone else who's out of step."

Artists, it could be argued, are solely preoccupied with death, given that the creation of art is an attempt for something of them to survive after death. Barnes leans heavily on other writers, and musicians, looking to them for wisdom and solace and example. Suicide, à la Hemingway or Hunter S Thompson, does not appeal: "I have never wanted the taste of a shotgun in my mouth. Compared to that, my fear of death is low-level, reasonable, practical." His mentors tend to have garlic on their breath: Montaigne, Flaubert, Zola, Ravel, Camus, the Goncourts, Stendhal - and Jules Renard, who is best known today for his journal to which Barnes refers throughout and whose remark, "One could say of almost all works of literature that they are too long", does not apply to Nothing To Be Frightened Of. As he acknowledges, Barnes shares more than his first name with Renard, not least melancholia. He was also ambivalent towards his mother. Barnes's mother is depicted as unsympathetic, driving his father into silence and himself to distraction. Once, he recalls, he wrote a short story in which a wife attacks her husband, who is having an affair, with heavy French saucepans. Neither of his parents appears to have been fans of his fiction. His mother's pride in her offspring was double-edged: "One of my sons writes books I can read but can't understand," she said, "and the other writes books I can understand but can't read."

His mother, who would have made a tart critic, outlived his father. Both their deaths were modern, in hospital, their bodies giving up on them, as bodies will. As Flaubert said: "No sooner do we come into this world than bits of us start dropping off." That seems perversely comforting. Two deaths described by Barnes seem well worth living for. Pavel Apostolov was a critic and persecutor of Shostakovich, whose Stalin-inspired committee drove the composer to the brink of suicide. At the premiere of his "death-haunted" 14th Symphony, Shostakovich asked the audience to be especially quiet because it was being recorded. In the middle of the intensely quiet fifth movement, a man jumped up, banged his seat and exited. It was Apostolov, who was widely believed to have done it deliberately to spoil the recording. In fact, in the middle of the "sinister symphony of death"; he'd had a fatal heart attack.

The other death concerns an old woman with no name, dying in the bed next to Barnes's mother. One day, she was visited by her husband, who kissed her and called her "love" and "darling" and pleaded with her to wake up and say something to him. "It pierced the heart (and the head)," writes Barnes, "and was only bearable by its edge of black comedy."

By coincidence, I witnessed something similar, when visiting my dying father in hospital a few months ago. Across the ward, a wife visited her husband, who was far gone in dementia. As he lay comatose, she sang in his ear, at first softly, then louder, a song that I like to think harked back to a time when they were young and happy and thoughts of death never crossed their minds.