If Chanel's Spring show skewered the art world for the oligarchs' supermarket it has turned into, Karl Lagerfeld went one better for Fall and imagined the whole world as a megastore—un grand magasin—under the sign of the double C. The shelves of his extraordinarily detailed set were stacked with more than a hundred thousand items, brazenly advertised at 20 or 50 percent more. No bargains in these aisles.

The labels of at least five hundred everyday products had been re-coded in Chanelspeak. Personal favorites included chic black cotton buds sold as bâtonnets élégants; boxes of handkerchiefs labeled Les Chagrins de Gabrielle; house paint in a color called Gris Jersey; detergent and potato chips; and, best of all, a hardware department that featured a chain saw with a real Chanel chain. The one that most entranced the locals was the recasting of a sac poubelle (garbage bag) as a sac plus belle (definitely not a garbage bag). There were also doormats printed with "Mademoiselle Privé." At show's end, as a locust horde descended on the shelves, those doormats were the day's key trophy—if you could get them past the security on the door of the Grand Palais. As Supermarket Sweep as the vibe was, the only goodies up for grabs were the fresh produce and the candies.

It was entrancing to see the fashion world's great and good transformed into kids in a candy store by Lagerfeld's spectacle. An epic celebration of consumerism was also an epic satire of it. An instant analogy was Andreas Gursky's gigantic 99 Cent diptych. (Lagerfeld was kicking himself that he hadn't thought to invite Gursky to the show.) As a piece of conceptual art, as a critique of pop culture, as a fashion show, it offered the juicy meat of an academic thesis.

Oh, yes, the fashion. Lagerfeld helped to make trainers the talking point of the Couture season. Here, he built a collection from the ground up on the footwear. "They had to continue," he said bluntly. "If you want to look really ridiculous, you go in stilettos in a supermarket." The very notion was antithetical to the guts of a collection that was just about the most democratic Lagerfeld has ever offered for Chanel. "That's exactly what I wanted to show," he said with an emphatic stab of a finger. So the Chanel catwalk accommodated an unusual variety of silhouettes and a massive range of options, from Cara Delevingne's raggy workout-wear to the sheath of clotted flowers that emerged at show's end. Couture's definite corseting inserted itself into the collection, but there was also a raggedy-hemmed smock dress and a black velvet jumpsuit, and a prevailing sense that Lagerfeld has no interest in offering directives. With today's overwhelming, irresistible extravaganza, he was saying that fashion's a supermarket. So you might as well shop.