'DOH, MAN,'' the grunge-clothed teenager sneers at Homer, after the Springfield Cat Burglar has defied his vigilantes and stolen the world's largest cuboid zirconia, ''I don't believe in nothing no more. So I'm going away to law school.''

For such gems we are indebted to James L Brooks, Matt Groening, and Sam Simon: genesis of The Simpsons, the cartoon series of ''America's most dysfunctional family'', first unleashed upon a grateful world in 1987.

Homer Simpson is the mince-for-brains patriarch; a goofy dogsbody at Springfield's nuclear-power plant. Off-duty, he sits in his undershirt eating and watching TV. His wife, Marge, has improbably blue big hair and a world-weary acceptance of our lot. Bart is the school-hating, mayhem-trailed 10-year-old son. Lisa plays saxophone; is a tad self-righteous. Maggie, the baby, sucks her dummy and looks on all with can-you-believe-this-guys? cynicism. And Homer's old Dad; a wrinkled, misanthropic cove who eats mush. They're all yellow with three fingers per

hand and quaintly shaped heads, and live in

the panicky town of Springfield: civic motto, Corruptus In Extremis.

Local characters include Chief Wiggum, the incompetent head of police; Mr Burns, the dastardly business-baron; Weyland Smithers, Burns's doting aide; Homer's ne'er-do-well drinking chums; a loquacious Indian shopkeeper; Krusty the Klown, a children's entertainer who hates children; and Marge's wicked, gravel-voiced twin sisters.

The Broons it ain't. Homer's attempts to better their lot end in invariable reverse; Bart's bids for fame in slapstick calamity. Half the cast teeter on the verge of nervous breakdown. Nor is the show shy of sending up American institutions, or even political subversion.

In a nation obsessed with sport and where every other soul counts her cholesterol level, the centre of chez Simpson is the TV sofa. There, Bart and Lisa regularly guffaw at the Itchy & Scratchy Show, the play-within-the-play cartoon-strip which is a very, very sick version of Tom and Jerry. It's all screamingly funny: tension-busting in the extreme for angst-laden fish farmers, newspaper columnists, Stornoway policemen, and electronic engineers. It's not just the animation (though that's slick, superb stuff). Nor the characterisation, though that's brilliant. It's all the in-jokes, movie-allusions and cultural references. In Marge in Chains, for instance, she's arrested for shoplifting; exuberant prosecutors screen the Zapruder film in an attempt to place Marge on the grassy knoll the day Kennedy was shot. In You Only Move Twice Homer is the foil of a supervillain plotting for world domination,

and helps bump off Sean Connery's James Bond. Bart's headmaster, of a fraught afternoon, cackles manically and starts talking to his mother at the Bates Motel. Real-life personalities - they include Henry Kissinger, Bob Newhart, Tito Puente, and The Who - have won walk-on roles.

Bart - the actress who voices him, Nancy Cartwright, appeared in Scotland last week - is the programme's driving force and, essentially, its moral norm. Children by the million everywhere can hurl his catchphrases: ''Don't have a cow''; ''Eat my shorts!'' He is perennially in trouble, wreaking mayhem on a catastrophic scale. He is, in the main streetwise, insolent, knowing, and know-it-all. Bart gives his Dad cheek, is the despair of his teachers and, sometimes, is shunned even by his classmates. (It hurts most when they laugh at him.)

''America needs more families like the Waltons,'' intoned President Bush sententiously, a decade ago, ''and less like the Simpsons.''

That wasn't the least kind, nor fair. By contemporary standards the Simpsons are a remarkably old-fashioned bunch. Homer dotes on his wife and, despite proffered temptation, never dreams of cheating on her. The Simpsons eat en famille around a table - a concept so allegedly arcane that, last year, we saw advertisers kill off the Oxo family.

Bart himself, naughty and irresponsible as he can be, dotes on his parents and his sisters. We often see him lonely, humiliated, frightened, and misunderstood. There is something real about Bart, which is why he's on my computer mousepad and why young 'uns all over the world identify with him. I say ''young 'uns'', not ''children'', because in a true contemporary sense Bart is not a child. He is a small person. In some odd regards he is more mature than his parents. By dint of stature and age, however, he is at the mercy of their caprices, and folly, in a weird and scary world.

Take Cape Fear, when Sideshow Bob the psychopath is yet again liberated from America's penal system, having long assailed Bart with death threats written in blood. One is intercepted by Homer, who reacts in howling panic - then dissolves in a chuckle. ''Oh, jeez. It's not for me - only Bart . . .''

Fleeing into the Federal Witness Protection Programme, the family become ''The Thompsons'', hiding on a creepy houseboat in a yet creepier lake, where Homer does little for Bart's shattered nerves. One night he bursts into the lad's bedroom waving an enormous knife - he wants to share out chocolate fudge brownies. Minutes later he leaps back with a howling chainsaw . . .

Sideshow Bob does turn up, tying up the folks and cornering Bart with a blade; in surreal, characteristic fashion, Bart wins the day by persuading the nutter to sing the entire libretto of HMS Pinafore, buying enough time for the houseboat to ground and the cops to spring.

Bart's universal appeal is to children in a world which, in recent decades, has all but abolished childhood. Even 30 years ago, children dressed differently, talked differently, and behaved differently from adults. We wore children's clothes, not miniature versions of adult attire. Pre-teens affected no interest in pop music. Little boys did not dowse themselves in deodorant or slick their cowslicks with hair-gel. Little girls did not totter on high heels or platforms, or fret about their weight.

Children played. We did not play with expensive electronic toys, nor tour theme parks and thrill-rides with our parents. In fact, we spent little spare time with our parents, save to observe as they planted roses, messed with wood, or baked cakes. (I often think modern parents spend so much self-conscious ''quality'' time with their children that they actually damp a child's imagination; certainly, the modern kid tends to be an obese wee thing who doesn't spend enough time with his peers.)

Our childhood was one of exploration, of gangs and secret societies, of shady woods and ominous pools, and quaking bogs and innocent strangers upon whom we projected untold international villainy. We built huts from tree-branches, or elaborate alternative economies of such currency as ''trump'' cards and Dr Who books.

Bart Simpson has no such innocence. He has never known childhood. Consumerism, televised violence, mocking rock'n'roll, and an all-pervading cynicism about goodness, truth, and authority have soured his capacity for trust and idealism. He retains, though, a capacity for love; and, being yet small, and most vulnerable, he survives to divert our own grey three-dimensional world: a child for our season and an icon for the age.