Charlie Rose: Is the curiosity a shared curiosity, or are there different curiosities?
Melinda Gates: Well, we both have curiosity for lots of things. Bill, at this stage in our life, also gets more time to read than I do, quite honestly, with three kids in the house.
Charlie Rose: Yeah.
Melinda Gates: But the great thing is Bill will go read an entire book about fertilizer. And I can tell you even without three kids in the house, I'm not going to read a book about fertilizer.
Charlie Rose: Yeah.
Melinda Gates: But he loves to teach. And so as long as--I have time, we'll spend time talking about that.
Charlie Rose: So what is it about a book about fertilizer? I mean seriously?
Bill Gates: Well, fertilizers are very interesting.
Bill Gates: We couldn't feed-- a few peop-- billion people would have to die if we hadn't come up with fertilizer.
Charlie Rose: How do you find a balance in all this? Father, chairman of a major company, a foundation, and then all these other ventures? How does the balance come to you?
Bill Gates: I don't mow the lawn.
Charlie Rose: You found somebody to do that?
Bill Gates: Absolutely.
He has come a long way from that teenage prodigy obsessed with writing computer code. Over nearly four decades we've watched Bill Gates help lead the digital revolution with what he now admits was a fanatic and relentless determination.
[Bill Gates from 1990s meeting: You guys never understood, you never understood the first thing about this. I'm not using this thing.]
Charlie Rose: In the early years, there was a demanding guy, there was a driven guy, there was an obsessed guy. There was, some say, an arrogant guy. Have you changed?
Bill Gates: I've certainly learned. When I make a mistake, you know, and my thinking is sloppy, I like to be very hard on myself. Like, that is so stupid. How could you not see how those pieces fit together? And that way that you're, you know, very disciplined yourself, and careful about your thinking, you don't want it to extend out to when other people may not get something quite as quickly. It's like, uh, how come you don't get this thing?
Charlie Rose: Has he mellowed at all?
Melinda Gates: I hope any of us in life mature, right? We all mature. But look, I wouldn't have married Bill if there wasn't a huge heart. With all of the adjectives you just used about how he drove his career, which was very successful for Microsoft, there was an enormous heart always there.
No question Gates has softened with age - just listen to how he reflected on his often tumultuous relationship with the late Apple CEO Steve Jobs.
Bill Gates: He and I-- in a sense, grew up together. We were within a year of the same age. And, you know, we were kind of naively optimistic and built big companies. We achieved all of it. And most of it as rivals. But we always retained-- a certain respect, communication, including even when he was sick. I got to go down and spend time with him.