At the Muse?e Yves Saint Laurent in Marrakech [Photo/Fondation Jardin Majorelle ? Nicolas Matheus]

"I want to give haute couture a kind of wink, a sense of humour – to introduce the whole sense of freedom one sees in the street into high fashion; to give couture the same provocative and arrogant look as punk – but of course with luxury and dignity and style." So said fashion designer Yves Saint Laurent in 1983 on the eve of his exhibition at the Costume Institute of New York's Metropolitan Museum of Art, its first-ever show devoted to a living designer.

Vogue editor Diana Vreeland, who also curated the show, wrote the following for the introduction: "For 26 years, Yves Saint Laurent has kept women's clothes on the same high level. He is followed across the oceans of the world by women who look young, live young and are young no matter what their age… Half of the time he is inspired by the street, and half of the time the street gets its style from Yves Saint Laurent. His vehicle to the street is pret-a-porter – but behind it all, there are the superb designs of his couture workroom."

His influence on 20th-century fashion and beyond may be even greater than the peers he worked alongside – including Christian Dior, Hubert de Givenchy and Gabrielle Chanel – and his clothes and themes more referenced and appropriated by high and low culture alike. Although she died in 1971, Chanel, never one for modesty, had even pronounced him her spiritual heir.

What makes Saint Laurent's collection of work so distinct is that none of his predecessors and peers, despite their luminous names, kept their original clothes in the same way. While other houses buy their dresses back from clients to build their collections, in the case of Yves Saint Laurent, what went down the catwalk was what got kept. His longtime partner in business and romance, Pierre Bergé, who died earlier this month, told Vogue that one day, the designer said to him: "I adore that dress; we must keep it." And so they did.