New York Fashion Week came to an end in 2001 with a Marc Jacobs show because of tragedy: The morning after his extravaganza on Pier 54, complete with disappearing walls to access the after-party and Donald Trump in the audience, the planes hit the Twin Towers and the world changed.

And New York Fashion Week came to an end this season with a Marc Jacobs show that acknowledged that moment: A paean to lost optimism and lost friends, and a bouquet of memory.

“It has been 18 years and a day we will never forget,” read the show notes left on every one of the vintage white rattan fan chairs and iron park benches and wicker garden-party seats arrayed sparingly at one end of the cavernous space, like little clouds. “This show, like that show, is a celebration of life.”

It was also about, wrote Mr. Jacobs, who dedicated the show to a friend who died in the Towers, how “we continue to learn from our past.”