When Anthony Burgess, interviewing Yves Saint Laurent for The New York Times in 1977, asked the designer how he saw women, his response was “as dolls”. Or that's what Burgess thought he'd heard. What Saint Laurent actually said, in his halting franglais, was “as idols”. Two small letters, one giant leap for womankind.

Of course the designer had said idols. This was the man who'd given women shoulder pads, safari suits, trouser-suits (Marlene Dietrich wore them in the Thirties, but cobbled together from men's tailoring; Saint Laurent recalibrated them for women and made them S.E.X.Y.), beatnik polonecks and more trousers (this in 1960 when most of them were still trussed up in full skirts and the fag-end of Dior's by then not-so-New Look), exaggerated cone bras (years before Jean Paul Gaultier pulled the same trick with Madonna), dresses that looked as though they had been ripped from the canvasses of Mondrian and Picasso, thereby demonstrating how a humble mini-shift could literally be a work of art - and transparent clothes.

All this sprang from his mind at the point when women were beginning to stride into the workplace into serious jobs, ditch the constricting girdles of their mothers and explore the free love that came with the Pill. When they wanted to tune in and drop out for a while, he gave them hippy de luxe. In fashion, timing is second only to talent.

Of course, from today's jaded perspective, surrounded by the flotsam of a thousand scantily dressed Z-list starlets, a see-through dress might not look like progress, but at the time - and what a time, it was 1968 - it was revolutionary, liberating, shocking. Look no bra! Look, lots of black women on the catwalk! (More than today probably.) Look, luxurious, functional clothes that, when required, seem the definition of bourgeois and prim but have a delicious, subversive kick (see the timeless wardrobe he conjured up for Catherine Deneuve's high-class hooker in Belle de Jour). Incidentally, Deneuve wanted him to shorten the hems in keeping with the current lengths, but he insisted, in a flash of self-presumption, on keeping them just above the knee, so that they would be timeless. Good call - and what self-belief.

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In fact, for a man who manifested every outward sign of being chronically insecure (his lover, business partner and Svengali-esque mentor, Pierre Bergé, famously said that Saint Laurent had been born with a nervous breakdown), he had an unerring sense of his own genius. Not content with turning the elements and subtext of female fashion on their head, he spearheaded a revolution in the way women had access to fashion.

Broadly speaking, before Saint Laurent set up his own house in 1962 (having being chief designer at Dior from the precocious age of 21), high fashion was available only to a tiny minority of wealthy women who had the time and means to fly to Paris for individual fittings of bespoke clothes that could take weeks to make. Saint Laurent boldly turned his back on this moribund system, pronouncing haute couture dead, and staked his reputation on the emerging trend for ready-to-wear fashion - still high-end, but far more democratic and more widely available than couture had ever been.

There are other riddles. For someone pathologically shy, he had a homing instinct for scandal - posing naked in his own advertising campaigns and naming a perfume Opium in the 1970s, despite having cultivated an array of calamitous addictions from which others might have preferred to divert attention. For a heady time in the Seventies, when Paris seemed to be the cultural centre of the world, he was at the centre of Paris, hanging out with artists (Warhol), dancers (Nureyev) actresses (Deneuve), socialites and writers (Thadée Klossowski). No wonder Bianca Jagger chose a white YSL tuxedo jacket when she married Mick in St Tropez in 1971, thereby anointing YSL as the high priest of all that was groovy, modern, glamorous and yet classily, classically timeless. Clever girl. The marriage may not have lasted, but the pictures look terrific - still.

While we're on the subject of contradictions, let's not forget that this notoriously fragile figure notched up three score years and eleven, although he stumbled from a beautiful youth straight to old age, missing out middle age.

Perhaps longevity was the cruellest paradox: trapped in a gilded world of ever diminishing returns, he spent more than 20 years cannibalising his own work, producing collections that became pale ghosts of their previous glory. Like politicians, many designers' careers end in failure and although the standing ovations continued, they stemmed from respect for his past achievements - and relief that he was still alive.

Knowing when to retire wasn't Saint Laurent's forte. But his legacy more than makes amends.

Lisa Armstrong is fashion editor of The Times

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