IN THE END, when the money is lost and the records broken, only style remains—a handful of gestures that recall a life or an era. Napoleon is dust, but the men at a dinner party still wear buttons on their sleeves because the Little Corporal wanted to stop his soldiers from wiping their noses. Arnold Rothstein was buried ages ago, but wise guys still carry cash in a roll in their front pockets because the gangster rumored to have fixed the World Series wanted to get at his dough fast. True visionaries are imitated not only by those who knew them but by those who knew those who knew them—culture is people copying people they've never met. Over time, the names are forgotten, but a few habits survive. In the last half century, there was perhaps no man more imitated than the late Gianni Agnelli, the Italian industrialist, chairman of Fiat and playboy of playboys in the jet-set age. When you see a kid wearing his watch or tie just so, you might be seeing a copy of a copy of Gianni.

His style was about more than clothes—it was an attitude, a philosophical response to absurdity. Watching him could tell you how to live, how to behave. In Italy, they call it sprezzatura, making the difficult look easy. Americans are gonzo, a spirit personified by Hunter S. Thompson, who defined it as a man who learns to fly by falling out of a plane. Agnelli might look gonzo—especially on nights when he showed up in boots and an ill-fitting tie—but was, in fact, sprezzatura; he knew how to fly all along. "When he was not perfectly dressed, it was contrived," says Taki Theodoracopulos, the writer, columnist, socialite and son of a Greek shipping tycoon. Taki is one of the few surviving members of Agnelli's social circle. "The tie askew, the unbuttoned shirt—nothing was an accident. Or, to put it another way, it was meant to be an accident, which made it even more stylish."

That slapdash manner is what people tried to imitate: the casual grace, the carefree quality that suggested Agnelli was living the life you would live if only you had the money, the pedigree, the confidence, the luck. He was charmed in the way of a man who gets dressed in the dark and still looks great. The hand-tailored shirt, the coat that didn't match—everything was wrong and everything was right. He was tall and slender, with wide-set eyes and the intelligent, worldly, wise face of a Continental. "You always had a sense that he was special, charismatic," says Ginevra Elkann, Agnelli's granddaughter. (She runs a gallery in Turin built around her grandparents' art collection.) "When he came in the house, you felt the atmosphere change. There was excitement. When he was around, you knew something was going to happen."

"He was elegant and wore clothes beautifully," says Taki. "He was meant to be a dancer, not an athlete. He was built like a boy, with narrow shoulders. The way clothes hung on him, it was just as the designers imagine it."

If you shut your eyes, you can see him in the society pages and gossip columns: in a blue one piece, skiing the face of a Swiss mountain, a cigarette hanging from his mouth; or standing before a line of new Fiats, pointing to his head, as if asking you to do the math—20,000 cars at a 100,000 lire apiece; or jumping nude from a yacht into the Mediterranean, looking not unlike Mickey tumbling into the night kitchen, in the Maurice Sendak book. You want to resort to big words to describe his persona: unflappable, punctilious, nonchalant—at once aristocratic and utterly informal. Claus Von Bulow told me Agnelli used to call at three or four in the morning just to say, "Tell me, Claus, what's happening in the clubs?" (The American version of this is Jimmy Cagney greeting friends, "What d'ya hear, what d'ya say?") "His life was his art," says Robert Rabensteiner, the fashion editor at L'Uomo Vogue, "the people he was connected with, the way he expressed the style of the jet set: Henry Kissinger, Jackie Onassis, President Kennedy. It was a beautiful life, and he lived it uniquely."