PARIS — The best part of Wednesday at Paris Fashion Week came in the middle — when Dries Van Noten showed his spring 2020 collection in the stark, cement back bunker of L’Opéra Bastille and the models’ glorious plumage transformed the dreary quotidian into a mesmerizing dream.

The gray morning gave no hints that such magic was in the offing. It began with an unsuccessful effort to juggle a reporter’s notebook, a Lanvin umbrella, a Lanvin rain poncho and a pair of Lanvin headsets over which the music was piped for the Lanvin show, which was outside in a park in the rain. (If this season’s runway shows have a theme, it is sitting-outside-in-the-rain.) This is not a complaint but rather a simple statement of fact. Plain old rain is not worth a complaint. Besides, there comes a point at which everything has gone so ridiculously sideways that all one can do is laugh. And Wednesday morning went so absurdly wrong that it left one doubled over, cackling and wet.

Besides, there were some fun clothes at Lanvin, from a cobalt-blue suit with eccentrically cut sleeves to cartoon prints inspired by an old comic strip, “Little Nemo in Slumberland,” which ran in the New York Herald in the early 1900s.

Lanvin was followed by a brief but expensive coffee at the Hôtel de Crillon where Eli Mizrahi, who describes himself as a party guy and entrepreneur, was ensconced to present his new line, Mônot. It is for party girls who can’t afford Balmain but who want the same over-the-top ostentation. Mizrahi is a whirlwind who happily announces that he lives on two hours of sleep per night, sources his patternmakers on Instagram and jet sets around the globe. And in the time it takes to down a cafe au lait, he has pummeled you with his backstory and his game plan and taken you down several rabbit holes involving dubious and unsuccessful business deals with Lindsay Lohan and Kim Kardashian West.

His clothes? Shiny, sexy, short, tight.

And then, it’s time for Dries Van Noten.

A pianist tucked into a corner played an anticipatory note, something in the vicinity of an A flat, as the first model walked onto the high runway wearing straight white denim trousers and a midnight jacket with a cinched waist. She was the quiet before the storm of color and pattern, before shapes exploded with volume and before fabrics began to float on the air.

Fashion has its creative limits. Designers can fuss with color; they can tweak the shapes; they can rework proportions. On Wednesday afternoon, everything seemed to be in wondrous, magnificent play. A bright fuchsia gown flowed open as a model walked. Tiers of scarlet ruffles tumbled over simple white denim pants. A white tank top was the simple foil to an elaborate skirt that trailed across the runway. Tiger stripes danced alongside lush florals. Skirts ballooned over slim trousers. Oversize trousers balanced generously proportioned blazers. Lustrous jacquards topped humble printed cotton.

There was so much going on at once that it could have easily become too much — a feast that transforms into grotesque gluttony with one morsel too many. But it was all perfectly balanced. The line — the invisible line that separates daring artistry from dramatic failure — was never crossed. The tightrope was walked.

The collection, in its controlled grandeur, was born from a unique collaboration between Van Noten and the designer Christian Lacroix. Long retired from fashion and focused on costume design, Lacroix was renowned for creating le pouf. It was a silhouette that defined the 1980s, a skirt that was inflated on air and crinolines and that came to represent the opulence of the period. Lacroix debuted this silhouette when he was the creative director at Jean Patou and it brought him such attention that he was wooed by the French fashion behemoth LVMH, which launched the Christian Lacroix brand in 1987.

For a time, Lacroix was the toast of fashion, and his influence was inescapable. He was a master at merging historical references and marrying divergent cultural influence into a patchwork of joyful celebration. But his extravagance was better suited to the rarefied world of haute couture rather than the more pragmatic sphere of ready-to-wear. His brand struggled for profitability for more than a decade until it was sold and transformed into a middling lifestyle company. The designer stepped away from fashion and has been immersed in costume design.

Jean Patou, by the way, was recently revived as simply Patou. And with Guillaume Henry appointed artistic director in 2018, the brand aims to be the “friendly” luxury house, which means that the collection is inspired by and presented on Henry’s chums and colleagues. And for its spring 2020 debut, Henry was in the atelier Wednesday to personally guide visitors through his thinking.

The collection is charming and youthful and without any of the 1980s extreme boisterousness that marked the brand’s last moment in the spotlight.

Van Noten turned to Lacroix when he realized that so much of the research he was doing for his spring collection kept bringing him to the French designer’s past work. Van Noten was looking to inject more grandeur and opulence into this collection, and he was fascinated with and inspired by Lacroix’s aesthetic. When the two finally sat down together at Van Noten’s invitation, it turned out that Lacroix was a customer of the Belgian designer’s menswear.

Collaborations have become quite common in fashion, but typically they are between a highbrow brand and a street-style company. The former is looking for a patina of cool, and the latter is trying to amp up its exclusivity. In other cases, companies will partner on a few special edition items. Just recently, Comme des Garçons partnered with Gucci on a collection of bags. And, of course, brands love to collaborate with a celebrity.

But the combination of Van Noten and Lacroix represents the coming together of two designers with similar sensibilities who are equally accomplished. The collection isn’t so much about the tension between two aesthetics but the harmony. And the result is quite special. The voice of each man is clear, but one never overshadows the other.

Is the work of the two men together better than what they have produced independently in the past? No. But it is different, and it is splendid. It represents a more relaxed and modern Lacroix. It is a more extravagant and indulgent Van Noten. The collection underscores the value of collaboration and cooperation — especially at the highest levels, when ego can so often get in the way of, well, everything.

Instead of two separate voices fighting to be heard, they are two men speaking together and delivering a message of eloquence and exceptional beauty. It is a particular message. And one that neither could communicate alone.

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