For today's Chanel spectacular, Karl Lagerfeld recast himself as Prospero, conjuring a magical underwater world from the raw stuff of fashion. The Grand Palais was transformed by huge, blinding white sea shapes—corals, shells, sea horses, stingrays—and Florence Welch arose like Botticelli's Venus on the half shell to sing "What the Water Gave Me." It was a bravura performance all around.

What the water gave Karl was the kind of acute overview that only he could turn into a dazzling collection. He'd been musing on the fact that forms as modern as anything designed by the architect Zaha Hadid have been shaped at the bottom of the ocean by natural processes taking millions of years. Chanel hasn't been in existence for quite that long, but there was an impressive, graphic modernity shaped by lengthy natural processes (Karl's thoughts) in most of the 80 or so outfits that strolled around today's massive set. Lagerfeld said he wanted lightness. He'd used new fabrics even he didn't know how to define. They brought an iridescent mother-of-pearl shimmer to the collection—the lightness literally shone through. That was also why Lagerfeld strung pearls, instead of belts, around waists. And Sam McKnight dotted pearls through the models' slicked-back hair, too.

Lagerfeld's aim was nothing too "Chanel" because, he sagely noted, there are already so many other people doing that style. Still, he insisted on something that was recognizably within the codes of the house. So there were boxy tweeds, drop waists, mille-feuille pleats, and an ocean of prettiness for the fans. It was enthralling to watch the way he insinuated his underwater theme into this traditional Chanel lexicon. The ruffles on one dress looked like sea sponges, the iridescent streamers flying from another like seaweed. It wasn't always successful—one of Stella Tennant's outfits sprouted unfortunate seaweed panniers—but how many other designers are there who are prepared to take such risks after six decades in the business? Strike that. Who has this much energy and creativity at any age?