“This is the way you want to live?” the Leading Player asks Pippin, who has decided to scale down his aspirations in favor of a simpler life. “No costumes?...And no magic!”

The line resonated deeply with at least one audience member. “What would life be without ?” Marc Jacobs recalled thinking. “Nah, not an ordinary life, not interested in that. Let’s do what we love, and do a lot of it.”

A lot is exactly what Jacobs showed, and it was extraordinary.

It’s too tidy to attribute Jacobs’ remarkable closure of the New York season on Thursday night to a single Broadway trigger; his thought process and work are seldom so linear. The show sprung as well from a lamp shade (the braid trim); past collections (Violet Incredible; military) long-invoked influences (Courtney Love) and the feeling that nanny oversight has taken the Goth out of Gotham. “It doesn’t seem like there’s much decadence anymore,” Jacobs said during a preview. “I’m not allowed to smoke in the park. I’m not allowed to walk my dog in the grass.” He then thought of instances of brazen self-expression — artist Paul McCarthy’s show at the uptown armory; the Burning Man Festival (even though he’s never been). And why fashion is so obsessed with new and modern. What, if anything, do those concepts mean, and who cares, anyway?

Somehow he fermented all of these swirling thoughts into a complex treatise on Victorian decadence: dark, dangerous and utterly compelling. The set, a highly stylized post-catastrophe beach littered with debris — broken lifeguard chair; frozen treats fridge; ancient, rusted bus — was designed to look like a stage set midway through deconstruction. The opening music, the theme from “Jaws,” got hearts racing beyond the palpitations brought on by the venue’s extreme heat.

But here was no wanton beach party. Rather, Jacobs went dark and weighty in fact as well as mood, to a degree that flew in the face of traditional notions of spring dressing and which, from a merch standpoint, will surely be controversial. The overall look was opulent, the day clothes either riffs on old, elegant officers’ jackets worn over re-fabricated surf shorts or loose-cut dresses and sweatshirts in thick velours. Evening presented a mesmerizing parade of slightly deranged-looking Victorian heroines in mourning — their darkness highlighted by intricate embroideries.

Though impossible to detail the work in these clothes (at least on tight deadline), it is not exaggeration to note that they approached couture in beauty and craftsmanship. Everything — including bags, moccasins and sandals — was embroidered, sequined, appliquéd, braided and tasseled beyond reason (Jacobs joked that there isn’t a whorehouse in all of France that could find enough trim for a throw pillow).

But then, as he sees it, fashion is the farthest thing from reason. Is a dress or jacket modern? Is it too dark for spring, too heavy, too this, too that? “It doesn’t matter,” Jacobs said. “All that matters is, do you want it or don’t you? Does it pull at your heart like fashion is supposed to? Like I said from Pippin, what would life be like without all of this?” So bring it on — the costumes, the tassels, the fringe, the dark magic.