Germaine Greer: The genius of Madonna

She can't sing and she can't dance. But the girl can talk. And that is what makes her a genius. Even if she looks ridiculous on the tour that rides into Britain this week

For years I was on Madonna's side. I wasn't exactly a fan, because I am of the opinion, shared by many, that Madonna can neither dance nor sing. What Madonna could do better than any other woman I know of was talk. She might have been a muscle-bound midget on stage, with synchronised squeals and squeaks instead of a voice, but in single combat she was a hero.

The first time I saw her on a US talk show she was wearing an unbecoming greeny-sludge-coloured dress and enough eyebrow hair to stuff a shirt, but she nailed every one of the host's knee-jerk reactions. She was sharp, funny, tough, and wonderfully brave. She used to call herself the "future of feminism"; Camille Paglia and I were happy with that. (The anti-pornography squad disowned the three of us.)

Madonna was secure enough then in her sense of herself to pick up a guy in a park and have his baby. Then she got DIY religion, married an Englishman (I could have told her that was a mistake) and crumbled before our eyes. She started telling us that all she wanted to be was a good wife and mother, even though she worked out so strenuously every day that she was honed to breaking point. Huge excitement greeted recent paparazzi shots of Madonna on the beach wrapped in white towelling; she needs the dead-white skin for her current incarnation as the ghost of Marlene Dietrich. Besides, when you're 48, bruises turn black and green before they fade. As Madonna's style is all grind and no bounce, she'll have been getting bruised on the Confessions tour, the European leg of which opens this very night in Cardiff.

People who can sing, dance and act are two a penny. Madonna has the one talent that really matters in the 21st century. The true art form of our time isn't music or dance or painting or poetry; it's marketing. Marketing is what makes a rubbish drink of aerated water plus caffeine, sweeteners and synthetic flavourings into a gadzillion-dollar global phenomenon and omnipotent symbol of the good life under capitalism. Dullards can't do transcendent marketing; it takes genius. It was Madonna's genius to realise that marketing was where it's at as long ago as 1979, which was when she registered Madonna as a trademark. Then she had nothing to sell. Now she is reported to be insisting that she be supplied with a brand new toilet seat at every venue on her current tour. The seat, still in its original plastic wrapping, must be unpacked and installed before her eyes, and removed when she leaves the venue so that it can't be sold on eBay. Now she could sell her used toilet paper.

In 1979 Madonna Louise Ciccone was 21 years old, and not yet two years out of suburban Detroit where she had been a cheerleader at Rochester Adams High School and won a scholarship to study modern dance and drama at the University of Michigan. At her ballet teacher's insistence, she quit college and went to New York with the drummer Stephen Bray and $35 in her pocket. She studied with Martha Graham and Pearl Lang and performed with the Alvin Ailey dance troupe and the Walter Nicks Dancers. Though she continued to collaborate with Bray until the Like a Prayer album in 1989, she moved on to other gifted men, Dan Gilroy, Jellybean Benitez, and Mark Kamins, all of whom were instrumental in creating the Madonna brand.

The precise nature of these relationships is difficult to define. When Madonna was explaining why she did not do the Confessions album with Mirwais Ahmadzai, who produced Music and American Life, she explained that after she and Stuart Price had worked together on "Hung Up" she "tried to do some other stuff with Mirwais but it didn't resonate... You meet somebody, and you're already going out with somebody else and you have this fantastic date with them and when you go back to this other person you're with all you can do is think about that other new person. I couldn't stop thinking about how fun it was to work with Stuart. It took me a minute to decide which boyfriend I wanted to have."

The entertainment press claims to remain astounded by Madonna's "uncanny" (that is, very canny) ability to reinvent herself, to rise like a phoenix year on year from her own ashes, but this is what marketing is about. Madonna is like any brand leader, regularly repackaged, constantly "new and improved". Madonna never wastes time: everything she does is advertising for the Madonna brand. She has always kept an ear out for whatever was happening on the underground; the trick was to recognise what could be commercialised and to go ahead and do it. Better still, find the people who were already doing it and get them to do it for you.

Madonna the style-setter is supposed to have an infallible instinct for identifying the next craze, whether it's wearing your undies on the outside, or a boy-toy belt or pink with everything, or Kabbalah or flimsy wrap-around dresses worn a size too small, or walking round the beach in a towelling tent. But something seems to be slipping. Fans have been left underwhelmed by the depressing news that this year Swedish clothes company H&M have based their autumn campaign on Madonna.

Madonna and her entire troupe of 150 were photographed in clothing they had chosen from the H & M collection, and the tour crew, band, dancers, roadies, the lot, are to be kitted out from head to foot in H&M clobber. No band I have ever heard of would co-operate in such an attempt to off-set the humungous outlay that goes into a blockbuster tour. Everyone laughed politely when Madonna first called herself a work-Nazi. Now it's not sounding so funny. On stage the diva will be dressed by Jean-Paul Gaultier. It was one thing to wear the famous Gaultier whirlpool stitched cone-bra on the Blonde Ambition tour in 1990; now the best we can expect is a rework of last century Eurotrash. In her dotage, Madonna has even agreed to have a Madonna tracksuit on sale in H&M stores from August. "The tracksuit comes in white and purple or black. The top is feminine and narrow with a yoke and gathering and the trousers are fitted at the top with wide legs and detailed with zippers." Maybe one day we'll have a Madonna walking-frame.

Madonna's hair has been all colours, and all shapes; her eyebrows have gone from normal through tufty to beetling and back again. Her features have gradually become so immobile that Dietrich is the only remaining option: lots of yellow hair, pale eyebrows, deep eye sockets and monumental cheekbones, and only rare, slightly bitter smiles. This suffering look is perfect, needless to say, for the pallid auto-crucifixion stunt that is "Live to Tell" in the Confessions tour. Madonna was upsetting people by portraying blazing crosses and sex in churches in her 1989 video of "Like a Prayer". In the Confessions tour she descends to the stage on a cross made of disco-mirror, as the female Christ, a cliché that was reworked by bad female artists half a dozen times in the late 20th century.

Madonna's massive cross was supposed to be covered with "diamonds and Swarovski crystals", which seems a bit excessive, especially as behind were projected images of African Aids orphans. Uncharacteristically, having got herself billions of dollars worth of free publicity that more than paid for the very ordinary cross in question, Madonna slightly caved in, and attempted to explain the stunt by claiming that, by portraying herself in a crown of thorns on a sparkly cross that is supposed to have cost $10m to make, she meant to encourage her audiences to give to charity. This is a mistake that she would not have made in 1989 when she took on the Catholic church with "Like a Prayer". Then she stuck to her guns, even though she risked losing a $5m deal with Pepsi; Pepsi blinked first, withdrew the commercial starring Madonna, thus breaking the contract, and Madonna kept her fee, as well as receiving a billion dollars' worth of free publicity.

This was a typical Madonna stunt and "Like a Prayer" was a typical Madonna product. Just as she had commandeered the name "Madonna" for her brand, she had always used the cross as a personal accessory, trumpeting the fact that she is a Catholic renegade. What is new about her latest attempt to milk the blasphemy motif was that she represents herself as a Michael Jackson-style victim. Like much of the Madonna product in the 21st century, the crucifix stunt appears only half worked out.

Weirder in its way is what the producers refer to as "the equestrian motif" of "Future Lovers". The concept dreamed up by Steve Klein was that wild horses emerging from a barren landscape would be tempted and tamed by Madonna. The old Madonna (that is, the young Madonna) would have known at once that this was a rubbish idea. Young Lourdes is already taking riding lessons; if she does ever learn how to handle horses, she will be more mortified by this egregious essay in amateur bestiality than by any of her mother's grosser forays into exhibitionism. On stage, the horses are danced by burly men in bridles and reins. Madonna, top-hatted, booted, hopefully not spurred, mimes humping the dancers, and then humps away on her own on an elaborate black-leather saddle arrangement covered with large silver studs, all the while making the stern Dietrich face.

The June issue of American magazine W carried 28 pages of photographs of Madonna by Steve Klein. For the session, stills from which are also being used as offical photos for the Confessions tour, six innocent stallions were transported to a Hollywood sound stage, ostensibly so that the diva could display her passion for equestrianism. As Madge can't stay on a hack for five minutes without plunging to the ground and breaking her billion-dollar bones, nobody was going to actually get her up on a stallion on the eve of a major tour. In most of the pictures and the video she isn't even in the frame if there is a horse in it, except for those in which the unfortunate horse has been persuaded to lie down. Then she is apt to be found lying on top of it dressed in an array of inappropriately skimpy clothing, nylon and polyurethane bra with spandex and nylon tulle panties and a vintage vest from Catwalk, or lace and lycra corset with fishnets, or polyurethane hot-pants. She is also to be seen striding about in riding habit, top hat and/or big gauntlets, and brandishing an array of riding-crops, one of which comes from Eros Boutique. In other even more absurdly stagey arrangements she is making like a ring-mistress, ringing a feeble change on her old dominatrix incarnation.

The producers of the Cardiff event are stuck with this no brainer. "Future Lovers" will open the show; two giant horses have been made out of disco-mirror to stand each side of the sound stage, but when Welsh TV was allowed in for a publicity preview it wasn't allowed to show them, because the producer, long-time Madonna collaborator Jamie King, wasn't sure that Mrs Ritchie would approve.

Madonna will be hoping that she draws more than the 60,000 who came to the U2 concert at the stadium in June last year. With tickets at prices from £55 to £160 no one's going to care whether the fans boo or cheer, as long as they're there.

Madonna begins the UK leg of her 25-city "Confessions on a Dance Floor" world tour tonight at Cardiff Millennium Stadium