The house was packed for Martin Margiela's 20th-anniversary collection, an occasion whose significance was sharpened by the swirling rumors—causing fear among the many Margiela wearers in the hall—that he is about to retire. (To get that one out of the way up front, a spokeswoman categorically denied that fashion's mystery man is going anywhere just at the moment.) What unfolded, in inimitable house style, was less a sentimental catalog of past hits than a reminder of the continuing relevance of Margiela's sidelong contributions to stimulating fashion over two decades and 40 collections.

First, there is the remarkable case of the narrow, slightly puffed Edwardian-shouldered jacket that dates from his first Spring collection, designed in 1988, which is still completely wearable now (it's being rereleased). And at the other end of the time line, there are the pointed shoulder pads of the 2006 bodysuits and jackets, with which Margiela triggered the beginning of a widespread silhouette change that is working its way through fashion now. The twist was that although the show was a revisiting of past collections, there were also slyly brilliant updates that put it right in the forefront of this summer's thinking. Circular-cut leather? Margiela first thought of that in 2005, and now the same geometries are blowing up all over the runways. Wigs, too—a favorite of the house since Fall 1995—have now spilled all over jackets in cuts that look like a Margiela comment on the current fad for fringing.

Almost each and every look had that then/now familiarity and surprise about it, and all of it was carried off without compromise on "incognito" models with their faces blanked out by stocking scarves and cascades of hair. At the end, though, the conceptual rigor gave way to pure silly high spirits as a perambulating birthday cake walked by, followed by a marching band and a horde of Margiela's lab-coated assistants. As usual, he wasn't among them, but he was apparently there watching behind the scenes. It's to be hoped Margiela was savoring the roar of approval that went up from the crowd.