Sometimes it takes a mistake to point you in the right direction. Francisco Costa¿s strong yet spare Fall show today made instant history of his much-maligned Spring collection.

First out was a funnel-neck coat in lead gray (the non-color of the season) with sloping shoulders and gently curving seams to the knee. From there, he moved on to an oversize cashmere waffle-knit pullover, a boxy wool-tweed poncho, and a tech-y piqué hoodie that looked lacquered in its stiffness. Some jackets came with notch collars that draped down the back to form a ridgelike V.

Whereas outerwear seemed to be about the negative spaces between clothes and bodies—a potentially pretentious concept that nonetheless produced results—dresses hugged every curve his models had. The trio of gowns that closed the show clung to their ankles. Easier for navigating a cocktail party was a strapless blue number with a molded bustier. Or a marble-print wool-felt sheath with face-framing collar that gave new meaning to the term "portrait neckline."

This was precise and assured minimalism, and sexy to boot. Costa has found the winning combination.