Giorgio Armani’s last fashion will and testament was delivered Sunday evening in the 18th-century Pinacoteca di Brera, one of the great art museums of Milan, before a crowd come to pay him homage.

Richard Gere, the actor whose career Mr. Armani’s clothes had helped launch in “American Gigolo,” was there, in an Armani tux, along with his “Gigolo” co-star Lauren Hutton. So was Glenn Close, who bought her first Armani jacket in 1983, and Cate Blanchett, an ambassador for the house. Spike Lee sat next to Samuel L. Jackson, both in midnight blue. Dries Van Noten came in from Venice, and Santo Versace from down the road.

They were there to attend what Mr. Armani had planned as the ultimate celebration of his half century in business: a runway show and the opening of a retrospective of his career, constructed from pieces in his foundation’s archive. A celebration he had been orchestrating for months, a spokeswoman said, down to the color of the Champagne, the 550 lanterns lighting the courtyard where guests would gather, and the lineup of models. Most of whom would appear in his signature two-by-two strut and which included a sprinkling of women who had walked for the house over the decades.

Mr. Armani’s death on Sept. 4 at age 91, however, transformed the planned party into a tribute: one that wasn’t sad, but rather elegiac. And oddly appropriate. Mr. Armani was a man whose dream was to design everything he touched. It was only fitting he got to design his legacy, too.

Because that’s how the combined runway show/retrospective functioned: as an effective crib sheet to everything Armani represented. Most of all ease, serenity and the power of an unwavering ideal.

Though the approximately 125 looks for both men and women in the collection were new, and the 133 outfits sprinkled throughout the galleries upstairs in an exhibition titled “Milano, Per Amore” spanned five decades, the extraordinary thing was how similar they all looked.

It was almost impossible to tell a suit from 1993 from one from 2011 from one that walked down the colonnaded catwalk. The jackets were either long and lean or neatly squared off at the waist, the pants had a swishy fullness, the sweaters were open-weave and the colors an earthy rainbow of sand, navy and greige. A relaxed self-assurance ran through it all, no matter how elaborate, or not, the surface encrustation.

And while there were sparkling gowns in emerald and sapphire suspended from filigree straps to close the collection — while the final model appeared like a blue angel or a benediction in the simplest long-sleeve gown with a portrait of Mr. Armani in a tuxedo picked out in beads on the bodice — the stars were the suits. Just as they were upstairs, amid the museum’s Renaissance frescos and major religious works.

It made for a marked change from the previous significant Armani retrospective: the controversial 2000 Guggenheim exhibition that later toured the world (controversial because the show followed a major gift by Mr. Armani to the museum, prompting charges of buying legitimacy). Less than a quarter of that show’s exhibits were suits, instead focusing on Mr. Armani’s more elaborate red carpet designs, as if to prove he was more than just a wardrober to the C-suite and break him out of the box that his success had constructed.

This time, aside from such looks as a bright red strapless ball gown (with hat) framed in an alcove and a slithery midnight blue satin skirt paired with a sheer knit at the center of a gallery of oils depicting the Madonna, suiting was in the majority.

It was as if Mr. Armani were posthumously embracing the fact that, beautiful as those sparkling gowns were (and are), they would not have the same transformative impact on fashion and culture as his deceptively simple soft jackets — the ones that changed how everybody dressed and are still influencing other designers. That it is those jackets that earned their place among the great artworks of history, because they also changed how we saw clothes, and the body.

Set against the Bellinis, Mantegnas and Tintorettos and beneath a towering Canova marble, in the final statement of a Milan fashion week that itself represented a generational shift, they rested elegantly, at peace.