When I say "miracle" I mean a kind of thing like a computer on a chip, or the internet, or the cellphone, that are really quite miraculous. Most people would not have predicted them, and their effect has been very, very dramatic.

The general idea of the rich helping the poor, I think, is important.

Lectures should go from being like the family singing around the piano to high-quality concerts.

Whenever you have a few setbacks, the idea that half as many children are dying now as back in 1990 and so... it was over 12 million a year, now it's less than 6 million a year. We have a clear path to get that under 3 million a year and we know what to do. And this generation of young Africans is a very large group.

Historically, privacy was almost implicit, because it was hard to find and gather information. But in the digital world, whether it's digital cameras or satellites or just what you click on, we need to have more explicit rules - not just for governments but for private companies.

At some point, that risk-taking private capital can take over, and have patents and trade secrets and things that let them lead the way, which happened with the steam engine and some other things, although with energy, the time of adoption is a lot longer than it is with, say, IT products or even medical advances, like drugs and vaccines.

The key for us, number one, has always been hiring very smart people.