Halfway through designer Hedi Slimane’s Celine show last night—after a fleet of tousled-hair girls in boot-cut jeans, patchwork rodeo skirts, shearling vests, and poetic blouses of the ‘70s Left Bank genre—I was suddenly imagining Dolly Parton on the stage of the Grand Ole Opry singing “Jolene.” It was all the denim, the models with their paws tucked into their pockets, and then there was a subtle shift, and Slimane introduced sparkle into the affair—shimmery bow-neck blouses and matching skirts, cardigans, many gold chains, and metallic, turban-like caps. Anyone who has observed fashion over the past half century knows that this chic ‘70s look is connected with the world of Yves Saint Laurent. As I write, I can see all those turbaned New York and Paris socialites in the pages of W magazine. In fact, in his Saint Laurent show the other night, Anthony Vaccarelli also had the twinkly ensembles with vests and luxe head wraps. Given the practice of using archival styles, nobody can be too surprised at the similarities this season between Celine and Saint Laurent, where Slimane previously worked. The thing is, though, the divides that once marked various aesthetic universes have been...