In a tawdry narrow street, in the rain, the geisha with fingers of white paint climbing her neck, with her fat obi (sash) hidden under an outer kimono so she looks like a hunchback, passes a row of Coca-Cola vending machines. The corrugations of her red paper parasol echo the corrugations of the steel security shutters in the foreground.

Many of Jodi Scott's photographs of geisha capture the cruelty and absurdity that result when their infinitely soft, artful, archaic world collides with the harsh, factory-made realities of modern Japan. It is only in pictures like these that we can begin to get close to the geisha, or even conceive of them as living recognizable human lives.

A row of geisha in their full onstage finery: their hair up and full of decorations, the collars of their kimonos low on the neck, and the knots of the gorgeous red-and-gold obi as big as rucksacks. We see them through aluminium-framed windows, fuzzy with honeycomb wire reinforcement.

A geisha making up: the dense matt white foundation, inspired by travellers' tales in the 16th century of the stark white complexions of the ladies of Europe, creates a blank page on which is painted a new face - a straight slash of eyebrows raised high up on the brow in permanent surprise, the mouth a tiny but preposterously full, sensual miniature of the real thing. At this stage she wears a white cloth wound around her scalp, and above that a hairnet. But what brings the picture to life is the fact that she is smoking a cigarette.

But who are the geisha? And what persuades them to follow such a strange, archaic path in life?

In the past, most geisha took up their calling through necessity, because their families - typically farmers - could not afford to support them any longer, or provide them with a dowry. For such girls, immersion from an early age in the geisha's world was simply a matter of fate, and a better fate than many that could have befallen them. Far better than to be sold into common prostitution.

Today, girls are not forced to become geisha. But as with most aspects of Japanese life, a sense of inescapable fate plays a large role in persuading girls to do it. Their mothers and grandmothers were geisha, so it is in the blood; or they are illegitimate, raised in orphanages, and a lucky break, a kind relative or friend of a friend rescues them from the terrible destiny (to a Japanese) of belonging nowhere. Once they have been rescued and taken into the geisha's hierarchical world, few have the wilfulness and ingratitude to break away.

The geisha is not a prostitute, though at some stage she will have to sleep with a client, and one day, if she is lucky and beautiful, a wealthy patron will buy her. "Geisha" means simply "art person", and the diminishing number of true geisha - Jodi Scott believes there are only about 1,000 left - train intensively from early childhood, mastering singing, samisen, dancing and the art of witty conversation.

The traditional world in which the geisha fully belong is both perfect and dead. Like the parallel world of the Kabuki theatre, it died, or at least entered its cryogenic phase, about 1870, after the Meiji Restoration ended Japan's Middle Ages.

After centuries of isolation, during which Japanese culture fed steadily on itself and in time almost forgot about the existence of foreign countries, consigning them to the realm of legend, the windows and doors of Japan were thrown open and, as when air rushes into a freshly opened Egyptian tomb, instant disintegration threatened.

With the faddish extremism that has long characterised Japan, the popular taste was suddenly for all things of the West - umbrellas, hairstyles, pocket watches, tail coats, literature, philosophy (Samuel Smiles's Self- Help, for example), music, dancing. Geisha culture, which had evolved steadily since its 17th-century beginnings, always on the cutting edge of demi-monde chic, was suddenly, hopelessly, irredeemably passe. The only course of salvation was to turn inward and preserve the geisha's arts, as if they were the mysteries of an order of esoteric nuns.

In Kyoto's Gion quarter the geisha still live communally, much like a religious order; and even in Tokyo, where they live in flats dotted around the city, there are few times when their lives cross those of ordinary people. The rickshaws that still run them between engagements in the Shimbashi section of Tokyo - such a bizarre sight amid the cars and lorries - and the high, blank walls and discreet traditional entrances of the ryotei (private restaurants) where they perform, are symbols of their separation from everyday modern life.

But, of course, that separation is an illusion. Geisha watch television, smoke, read stupid magazines, hanker after a kind, rich man and a stable life. Their business is to sing and dance for their guests, tell them salacious stories, pass on the latest gossip from the worlds of showbusiness and politics, get them merry and lead them delicately into a world of childish games and nonsense where they become insensible with drink and happiness. The geisha are a sort of school of ancient Japanese therapists; intimately both of this world and of one that is long gone.

All the pressures of the modern world are conspiring to drive the geisha out of existence. But what is really surprising is that, after 125 years of highly successful modernisation, the geisha survive at all. There is something wonderful - but something painfully sad, too - about these exquisitely cultivated and decorated creatures, both adrift and at home among a world of beer cans, bullet trains, pop stars, plastic slippers and fluffy toys. It's tempting to say it's the sadness of modern Japan, and perhaps it is

That's why you cannot really bear to look at pictures of geisha performing on stage, acting as hostesses in tatami-matted rooms, playing the samisen or walking in processions: such images are beautiful, arguably, but they are consummately inhuman. The human subject could be substituted by a doll, a mannequin, a waxwork or a hologram and it would make no difference.

And all the ambient imagery is so hackneyed now - from mossy rocks to paper windows, split-toed socks to lacquered rickshaws - that it leaves you cold and weary. Some tawdry intrusions from the real world - comic books, television sets, cigarettes, traffic lights, plastic powder compacts - are required to remind us that these women shit and piss and laugh and suffer like the rest of us.

: the indifference of most Japanese about their traditional culture, for example, and the slow but steady spread of feminism. In the past, the typical geisha was forced into the profession. Today, such imperatives no longer exist, so only girls who really want to become geisha go in for it. And there are not many of those.

But this not the remarkable fact