????Mellowing with age

????In his younger years, Gates' gimlet-eyed idealism manifested itself in stubbornness and self-righteousness, an unusual boldness, and a tendency not to suffer fools. Most people who have worked closely with him can recall more than one instance in which he reacted to a comment or idea by standing up and hissing, "That's the stupidest thing I've ever heard in my life."

????He hasn't lost that inclination toward intellectual arrogance. But in his philanthropic work, the shoe is sometimes on the other foot. He's not, after all, a microbiologist or a geneticist. Moreover, with age and maturity, Gates has become much better able to acknowledge what he doesn't know or when he's wrong.

????"The classic CEO needs to be right, or rather needs to appear to be right more than he needs to actually be right - and that's not Bill," says his pal Myhrvold. "Lewis and Clark were lost most of the time. If your idea of exploration is to always know where you are and to be inside your zone of competence, you don't do wild new shit. You have to be confused, upset, think you're stupid. If you're not willing to do that, you can't go outside the box."

????And that explains the third dimension of Bill Gates' new life - giving that "world-class curiosity" some room to run. His reading and learning have always been systematic. It's his nature. His father and sisters recall how young Bill would refuse to leave his room to come to the dinner table because he was too busy "thinking." But for many years, as he built Microsoft, his field of vision was of necessity rather narrow. One of the most important experiences that jostled him out of his single-mindedness was his first meeting with Buffett, on July 5, 1991. As Gates tells the story:

????My mom called me at the office to come out to Hood Canal for a Fourth of July barbecue because she wanted me to meet Warren Buffett. And I said, "Mom, I'm working." But she insisted. So I took a helicopter so I could spend my couple of hours there and then get back quickly and work on software.

????Then I met Warren, and I thought, "Oh, wow, this guy isn't just about buying and selling stocks and businesses. He is thinking about how the world works." And he asked me questions that I always wanted somebody to ask me, about why hadn't IBM (IBM, Fortune 500) been able to do what we had done, and how software gets priced, and why does one company have a defensible position. He wanted to understand the dynamics of the industry. To me it was way far away from, "What is your company worth?"

????Then he explained to me about how Wal-Mart (WMT, Fortune 500) had not only changed things in its business, but how it had an effect on newspapers because they thought of their advertising differently than individual local stores had. And he talked about how banking really worked in terms of credit risk. The whole time all I could think was, "Hey, I'll be smarter about running Microsoft after I talk to this guy." And so I stayed the whole day.

????Ever since then, Gates has tried to make more time to broaden his knowledge, and his capacity to absorb ideas has served Microsoft and the foundation well. But now reading, learning, and blue-sky brainstorming will be considered an integral part of his job description, and no doubt they will yield something.

????Think of his third office, the one equidistant from Microsoft and the foundation, as the billionaire-adult equivalent of his own room. It's a place for him to spend time exploring his own ideas, and occasionally trying to find an appropriate entity to pursue them, whether it be Microsoft R&D or someone at the foundation or one of the foundation's many corporate and nonprofit partners. He'll focus on ideas related to his philanthropy, but he also will spend a lot of time with the staff of Ph.D.s and inventors at Intellectual Ventures (IV for short), Nathan Myhrvold's Seattle-based skunkworks for discovering patentable new technologies. Previously IV hosted brainstorming sessions for foundation scientists, and Gates is an informal member of a group of IV partners and investors with more general interests that meets regularly. He plans to participate even more frequently after July 1.

????"I'm not going to create a company," Gates vows. "The foundation is the top priority. But there are some other things that I might help along. The scientific brainstorming with Nathan's group has led to a new nuclear energy startup, and I'm a funder and advisor to that thing. It won't be a huge amount of time, but the truth is, cheap energy that's environmentally friendly is a breakthrough that is more important for the poor than the rich. And the poor need fertilizer, more reliable seeds, and better agriculture too. They can't cut back their eating, because that's called starvation. So I'm investing in that."

????Myhrvold loves the irony of it all: "It's so funny: Here's a guy who never went to class when his poor dad was paying the Harvard tuition, and now the sheer love of learning has sucked him back in, hard-core. It's not like he needs a job. It's not like he's thinking, 'Oh, that would look good on my résumé.'"