Rowan Pelling: Beauty is a curse. Just ask Brigitte Bardot

Society is unforgiving to the lovely who lose their looks. Better to be middling, but with potential

I have read The Line of Beauty three times - an act of literary devotion you rarely make in adult life unless you find yourself on the panel of a book award, as I did when the novel carried off the Man Booker Prize. I know Hollinghurst's book in the way you usually only come to know The Very Hungry Caterpillar or an A-level set text; the characters feel like members of my extended family and I have a clear idea of their physical presence, although Hollinghurst never restricts the reader's imagination with too many exact physical details.

Instead, the silkiest of brush strokes gives a precise sense of the person: "Catherine was slight but physically reckless; what drew boys to her often frightened them away."

Nick Guest, the young, gay Henry James devotee whose viewpoint and experience steers the narrative, is even more lightly etched in terms of concrete physical attributes. My own sense of the character is that he's a pleasant-looking, clever, subtle boy, whose physical presence is the very opposite of imposing, and it's precisely these qualities that allow him to be a keen observer of the gilded world he infiltrates and an unobtrusive house guest to a wealthy Tory MP's family.

So I was astonished to see the actor chosen to play Guest in the current BBC2 television adaptation of The Line of Beauty. Dan Stevens is a youth so spectacularly attractive, with his piercing aquamarine eyes, harlot's lips, mop of thick wavy brown hair and spookily symmetrical features, that most mere mortals would gladly crawl over broken glass and dog pooh for the faintest chance of air-kissing his sublime Renaissance angel ass.

While I'd be the first to admit that this super-abundance of male pulchritude makes agreeable viewing, it also makes a bit of a nonsense of one of the novel's key themes: Guest's single-minded pursuit of a particularly refined aesthetic - in both things and people - to the point of amorality. Surely the first tenet of beauty is that it's most fascinating to those who don't possess it? Conversely, those who move within beauty's sphere, who are born to its particular grace, can never feel its benediction as clearly as those who live without it but yearn for its touch.

In Hollinghurst's novel, Nick Guest pines in vain after golden boy Toby Fedden, then pursues long-lashed Lebanese millionaire Wani Ouradi: "Beautiful as a John the Baptist painted for a boy-loving pope." In both instances Guest ingratiates himself as courtier to the object of desire. But why would a man who's beautiful as a god himself have to go to such obsequious lengths to attract the notice of another human being? Or put it like this: how often do you see Johnny Depp paying court to anyone? If the Guest of the book were as blindingly handsome as the Guest of the TV series then, in Top Trumps terms, his points rating would have made him as much a force to reckoned with as the Feddens' combined wealth, privilege and status - destroying the whole point of the drama.

There are different rules for the beautiful; they cut a swathe through crowds like Moses parting the Red Sea. Everyone behaves differently in the presence of extraordinary beauty, just as they do with great wealth, celebrity and royalty. Life is much less effortful for the beautiful. Why get a job when people will happily pay you just for being indecently gorgeous, for lending your good looks to their dreary magazines, parties or products? When they will pay £60,000 for one kiss? (When Jemima Khan and Kate Moss snogged for charitylast week, everyone perceived an iconic and ironic tableau of beauty saluting beauty. If two plain women were to do exactly the same, it would be just two ugly dykes getting it on.)

When beautiful people have qualifications or attributes beyond a talent for being photogenic, then everyone gives them excessive credit for retaining the ability to think and function. Models with A-Levels are afforded the awe usually reserved for Watson and Crick. Kate Moss is talked of as though she were the living incarnation of Dorothy Parker because she retains a modicum of humour and attitude in a sea of androids. And the brownie points beautiful people get for saying please and thank you, and giggling at other people's jokes. If I read once again how nice Keira Knightley is I may have to shoot a kitten.

Nevertheless, I truly believe that excessive good looks can be a handicap. There is usually something curiously unfinished about beautiful people. Their smooth glide through life and the fawning cushion of deference bestowed upon them by awe-struck admirers leaves little of the patina that helps form character and sex appeal.

Sex with beautiful people is all too often an inhibited act of homage rather than an earthy, passionate meeting of equals. The most celebrated seducers and grandes horizontales in history have rarely been the most startlingly good-looking people of their age. The ravishing rarely develop the feral brand of sex appeal and razor-sharp wit that typifies the great sack-artist.

The ideal condition is to be granted moderately attractive looks. You can work with this kind of face-putty over a lifetime and often find you look better at 40 and 50 than you did at 15, à la Hillary Rodham Clinton. But extraordinary beauty is bestowed with an inbuilt curse - the gawping world will always measure you against your 20-year-old radiant self and find something lacking. There can be a kind of savagery in the measurement, as when we look on the adult Brigitte Bardot.

By the end of The Line of Beauty, the world punishes Wani for his loss of looks by averting its offended gaze. Those who live by the looking glass can die from its icy reflection, and although no teenager would believe me, life is kinder to those not given the mortal beauty that tempts you within its unforgiving frame.