If you haven’t already visited “Chanel,” the exhibit of the fashion house’s iconic designs currently on view at the Metropolitan Museum of Art – wait. Last week, the Drouot auction house in Paris hosted a historic preview and sale of the 20th century’s other modern master: Paul Poiret. Those fashion-lovers lucky enough to call and order a catalog before they sell out will receive a subtle lesson in Chanel that even the Met doesn’t show. This beautifully produced, two-volume boxed set illustrates the entire Poiret family archive.

The sale of this archive, “La Creation en Liberte: Univers de Paul et Denise Poiret 1905-1928” (“Freedom in Creation: The Universe of Paul and Denise Poiret 1905-1928”), began May 10. That afternoon, the neighborhood of St. Honore was rife with fashion dealers, designers, and museum curators lugging their heavy black-and-white catalogs through the nearby shopping arcades and shooting espressos in the bistros of rue Richelieu. Throughout the city, boutique clerks, especially vintage boutique clerks, were remorseful that they couldn’t attend the historic sale and pick up a token item with which to remember the designer, long-eclipsed by Chanel, who died in penury and obscurity more than 60 years ago: a purple stocking, a feather, or a swatch of fabric.

Paul Poiret (1879-1944) is considered by many to be the first modern designer. In 1905, after his apprenticeship at the House of Worth, the avant-garde couturier married his muse, Denise, and the couple took Paris by storm with their audacious designs, body-freeing sheaths, and bold, ethnic-inspired prints. Poiret discarded bras and corsets; commissioned graphic, orientalist-inspired patterns by artists such as Raoul Dufy; embraced cloth from around the world; and, perhaps most legendarily, did not restrict his design and sensibility to clothing. He branded himself to perfumes, housewares, soirees, an art school named Martine, and even a short-lived fashion magazine. (And you thought Karl Lagerfeld was tireless!) His rose emblem preceded Chanel’s camellia – or gardenias and boxwood, as the Met would have it – by decades.

The clothing and objects up for auction – designed exclusively for Denise and the Poiret children – lay forgotten and undisturbed for almost a century, until granddaughter Sophie discovered three trunks full of garments, art, samples, textiles, children’s clothing, hats, and shoes in her attic in 2002 when an auctioneer was called in to poke around before a move. Denise had amassed them in 1928, following the couple’s divorce. “She thought the trunks were empty, and she just had the furniture, but when we opened them, they were full. And it was only when I then saw the labels I realized they were by Paul Poiret,” auctioneer Pierre-Emmanuel Audap told Agence France Presse last week. Mr. Audap then spent three years working with couture expert Francoise Auguet, the dealer of 20th-century Parisian couture appointed by Sophie, who prepared the garments and cataloged the belongings that defined the life of Paris’s most fashionable woman.

On offer to anyone willing to spend $50,000 for a pair of beaded evening shoes from 1924 or $167,000 for a driving coat made from a single piece of fabric in 1914 – two auction records set at this sale – were archetypes of contemporary fashion. Here is Poiret’s laboratory,” said New York couture dealer Mark Walsh, who was attending the preview and sale with his business partner, Leslie Chin. “You can see him working out ideas on Denise, experimenting, taking risks with the empire lines and ethnic details.”

“If it ever shows up at auction, Poiret couture usually dates from the 1920s, and it’s typically the theatrical stuff,” Ms. Auguet said. “Rarely are examples available from 1910s, nor are the domestic items like the lingerie he created for Denise.” Ms. Auguet has been dealing for 35 years, launched couture sales at Drouot in the late-1980s, and owns the popular vintage boutique Rag Time on rue l’Echaude.

The sale began with samples of colorful floral Art Deco wallpaper, fabric designs, and housewares created by Martine students in 1922, and then briskly moved to the section titled “The Meadow Hours.” This collection of early examples of summer blouses and dresses – including the Directoire-inspired “Delphinium” dress of 1912, a fantastically modern precursor to the flapper sheath with bare arms, plunging neck, and loose sash at the waist – hats, shoes, and children’s clothing was in immaculate condition. By the 15th lot, the tone was set: Everything would be fetching 10 times the estimated price. That’s when I gave up bidding on the cobalt-marine blue wig (estimated at a few hundred euros) – the only idea presented at this auction not being revisited by contemporary designers with their Poiret-inspired embroidery, flowing skirts, layering, and sashed waists.

Poiret’s vibrant, embellished clothing – the first examples of what we today call boho-chic – was a foil for Chanel’s monochromatic urban uniform of tailored separates. If Chanel, who paired down form to its essential components, is the Picasso of modern dress, then Poiret, the fantasist-colorist, is the Matisse. It’s impossible to imagine contemporary fashion – or art – without both traditions.