It was supposed to be a temporary fix. Steve Jobs was Apple's "iCEO," and the iconic first letter didn't stand for Internet. It stood for interim. In 1997, when Jobs returned to the company he cofounded, he insisted he was there only to do an overhaul. The floundering Apple was like a wrecked jalopy, he said, or an old girlfriend fallen on hard times. He'd make it shine again, then split. Apple's board asked him to stay permanently, of course, but he demurred, explaining that he already had a company to run. "I felt I was pretty committed to Pixar and couldn't do something else, didn't want to," he told me on the week of his return to Cupertino.

"And you will absolutely not be the CEO of Apple?" I asked.

"My name is not in the hat to be CEO," he said.

It turns out there was no hat. Interim or not, Steve Jobs inhabited the chief executive role so thoroughly and masterfully that eventually people stopped asking who would take over for him. The 2000 announcement that Jobs would stay was anticlimactic. By then he was not only Apple's CEO but someone who embodied the platonic ideal of that position.

Thus the poignant resignation letter that Jobs posted on August 24, 2011, ends an era. Though Jobs will remain at Apple as chair—and Apple says he will be an active chair—a milestone has passed. The greatest CEO in memory is no longer a CEO.

What makes the perfect chief executive? Understanding customers and what they want, even if they don't know it yet. Mastery of market dynamics. The acumen of a poker champ. Commitment to excellence and brutal rejection of "good enough." Accountability when things go wrong. Charisma that makes product launches as exciting as a Springsteen show. Steve Jobs had it all, in abundance. (Not necessarily included in the ideal skill set is a tendency to witheringly dismiss anything that fails to meet his "insanely great" standards. And a penchant for secrecy that makes the NSA look like the public library. But maybe those darker traits can't be separated from such an exacting, oversize personality.)

He also had a talent no other CEO could boast of—the ability to defy the corporate equivalent of nature's law. "If anybody's going to make our products obsolete," he once told me, "I want it to be us."

The bane of Silicon Valley is the Innovator's Dilemma, which says that once a company takes the lead in any given domain, it becomes less able to come up with radical innovations in that field. Jobs seemed to have discovered a powerful counterforce: the Innovator's Gyre, where each dizzying breakthrough leads to another. The iMac begat a digital hub strategy with iTunes, which begat the iPod. The music player eventually served as a launchpad for the iPhone, which in turn evolved into the first massively successful tablet, the iPad. And the iPad's innovations are now inspiring Apple's computers, as the Macintosh gains a gestural interface.

Some chief executives view a successful run as a springboard to loftier pursuits—politics, philanthropy, the helm of an even bigger firm. For Jobs, running Apple was the pinnacle. After receiving treatment for a life-threatening cancer, all he wanted to do, besides enjoy his family, was run Apple. For the past few years, every time I or another journalist interviewed him, he would reiterate: I love this job. Even during his medical leave earlier this year, he not only kept up with Apple's big decisions and products—reviewing key releases, negotiating with tech and media honchos—he also took star turns at two Apple launches. He did not iPhone it in but was, as always, ruler of the stage. Instead of enervating him, those moments seemed to energize him.

And now he's no longer CEO. It's ironic that Jobs made his decision only days after Hewlett-Packard said it might sell off its PC business. 1 I once observed to Jobs that when he and Steve Wozniak started Apple, there was no template for how two young guys should build a big corporation. Jobs corrected me. "There was a template," he said, "HP." Also founded by two young men, it had been a pillar of Silicon Valley's values and standards for decades, and he saw it firsthand. "Woz and I both worked there," he said. "There would never have been an Apple had there not been an HP."

Now, of course, HP may be leaving the game and there is another company that is the inspiration for all young founders. 2 "When we started Apple, we took values from Hewlett-Packard as best as we understood them," Jobs said. "We took things from other companies we admired, and to now be in that role for some new young company is wonderful. I'd like to think that in our own small way we've done some of that."

Jobs knows that he and Apple do provide such inspiration, and not in a small way. Though he returned to Apple as iCEO, he became the CEO, setting a standard for leadership that was as impossibly high as the standard he set for his products. Which creates a problem for the company he gave so much to: the Successor's Dilemma.

Senior writer Steven Levy (steven_levy@wired.com) interviewed Bradley Horowitz, lead developer of Google+ for issue 19.10.

Note 1. Correction appended [Sept. 29, 1011/19:00]: This story previously reported, incorrectly, that Hewlett-Packard has left the PC business; in fact, it has only said it is considering doing so.

Note 2. Correction appended [Sept. 29, 1011/19:00]: This story previously reported, incorrectly, that Hewlett-Packard has left the PC business; in fact, it has only said it is considering doing so.