If I had a dime for every time I've heard it, I could start another business: Entrepreneurs are passionate people, great at building companies, but only to a certain level.

As their enterprises reach maturity, these impatient, impetuous founders need to be replaced by "professional" managers. It's a stereotype that's become a truism. In VC land they even have a name for the problem: founderitis.

The most recent public eruption of this hypothesis occurred when Amazon.com celebrated its 10th anniversary, and the media openly wondered whether it was time for Jeff Bezos to surrender control. Give me a break. That same logic came close to destroying Apple. You know the story: In 1985, convinced the company had outgrown its founder, the board dismissed Steve Jobs and handed the reins to John Scully--a packaged-goods guy, a branding maven, whom Jobs had wooed from Pepsi two years earlier. Scully, of course, failed either to expand the company in the computer market or to innovate elsewhere, and in 1993 was replaced by Michael Spindler, who in turn was replaced by Gil Amelio--neither of whom did much better. Jobs returned as interim CEO in 1997, dropped the interim in 2000, and the rest is white-earbud history.

Business is faster-moving and more unpredictable than ever--precisely the conditions that cry out for more, not less, of the founder's restless spirit.

The lesson is obvious. The notion that entrepreneurs outlive their usefulness is both stunningly wrong-headed and potentially dangerous--especially now. It's universally acknowledged that today's business environment is faster-moving and more unpredictable than ever. And those are precisely the conditions that cry out for more, not less, of the founder's restless spirit. Indeed, the very skills and qualities that gave rise to a business at the outset are what's needed when companies find themselves in a constant state of re-creation. No business, however "mature," needs mere tending. But all businesses require sparking. Entrepreneurship needs to be a chronic condition.

You don't have to be an entrepreneur to understand this. Just look at General Electric, where CEO Jeffrey Immelt recently introduced a series of initiatives designed to change the behemoth's culture--encouraging an entrepreneurial climate that values risk-taking and innovation, moving the corporation beyond Jack Welch's legacy of process and fanatic focus on bottom-line results. Considering GE's bellwether status, it's not hard to imagine other corporate giants embarking on similar paths.

Which isn't to say that founderitis is not a real concern. For every leader with the flexibility and creativity to lead a company through periods of change, there are others who can't make it up the next hill. But this problem afflicts all CEOs, not just entrepreneurs. In fact, in today's world, I'd argue that entrepreneurs are less likely to lose their way than the so-called professionals. Still, we are vulnerable. We always must be prepared to fall out of love with the business we fell for head over heels and alter strategy or direction in an ongoing drive to create something new and better than what we had originally.

Those who argue that it's time for a Jobs or Bezos to pack it in are forgetting that the entrepreneurial mindset is, by definition, protean and fluid, able to identify opportunity where others see chaos. If we are truly in a new world in which change is the governing constant--and I believe we are--then it's time to move past the argument that certain leaders are best suited for certain times. This isn't to say that entrepreneurs don't need to plan for succession, or that there might not come a point where they simply get bored. What it does mean is that there is no formulaic time to leave. Anyone who tells an entrepreneur such a moment has arrived probably does not have his or her best interest in mind.

Adam Hanft is CEO of Hanft Unlimited, a Manhattan-based consulting, advertising, and publishing firm. For more Grist, visit Inc.com's Marketing Resource Center.