There's always been a lot of information about your activities. Every phone number you dial, every credit-card charge you make. It's long since passed that a typical person doesn't leave footprints.

Hopefully, whether it's energy or child vaccines, the case of the many benefits helping countries so that they are stable, so these refugee problems that have been troubling for Europe - a little less so for the U.S. but, even so, a lot of controversy there - these things are why the future's going to be better than the past. People really do look to the United States, so we'll be there making the case.

Measles will always show you if someone isn't doing a good job on vaccinations. Kids will start dying of measles.

In ninth grade, I came up with a new form of rebellion. I hadn't been getting good grades, but I decided to get all A's without taking a book home. I didn't go to math class, because I knew enough and had read ahead, and I placed within the top 10 people in the nation on an aptitude exam.

Climate change is a terrible problem, and it absolutely needs to be solved. It deserves to be a huge priority.

I've always been amazed by Da Vinci, because he worked out science on his own. He would work by drawing things and writing down his ideas. Of course, he designed all sorts of flying machines way before you could actually build something like that.

But the improvements will happen faster and last longer if we can channel market forces, including innovation that's tailored to the needs of the poorest, to complement what governments and nonprofits do. We need a system that draws in innovators and businesses in a far better way than we do today.