How to satisfy the contrary demands of women's fashion desires? It's a problem vast enough to send many designers crazy, or to make them stick their heads in the sand and fall back on safe retro formulae. At this moment, when fashion finally feels like it's teetering on the brink of something new, that isn't good enough. And for designers of Alber Elbaz's caliber, the only way is to face up to complexity. For Fall, he walked a knife edge, balanced between rigorously architectural urban simplicity and explosively fierce embellishment, sourced somewhere in African tribalism.

Before his show, Elbaz reeled off the loops he'd put himself through to get there: "Women ask for masculine tailoring, but they want to feel fragile. They want daywear, but buy evening. I designed a whole lot of draped things, but then it looked like too much. An overdose of fashion." His change of heart came on returning to the studio after a meeting at the U.N. to learn about a role he is about to take up as a UNICEF ambassador. It cleared his mind to work on plain, molded city clothes on the one hand, and made him think about Africa, his birthplace, on the other.

The link between the two presented another of the season's essays on powerful womanhood. For day, it began with no-nonsense, clean silhouettes cut from matte stretch materials with a molded structure; dresses and coats were cut roomy in the shoulder, tapering to clutch the hips. The technical starkness was gradually steered away from minimalism-by-rote with the addition of chunky metal and rock-crystal jewelry and beaded spine-tracing zippers, building up to dynamic feats of diagonal pleating that crossed the torso in one direction and shot across the hips in the other.

To a soundtrack of fast-paced drumming, Elbaz kicked up the emotional speed with waves of cocktail and eveningwear that spanned simple jersey togas, erotic lace transparencies, glamorous ostrich- and marabou-decorated dresses, and intensely bejeweled and feathered gold or green-tinted lamé. In real time, it was visually sensational and layered with dynamic contradictions, like the fact that baseball jackets, sweatshirt shapes, and track pants were the carriers of some of the most exotic embroideries. That might not wholly read in photographs—blame the grim lighting in the inhospitable warehouse on the outskirts of Paris that Lanvin and other luxury-goods houses have inexplicably taken as a venue recently. But Elbaz's contribution to the season is guaranteed to keep the fashion world thinking for a long while yet.