Investing in tomorrow's technology today is more critical than ever.

We're creating this alliance, GAVI, that has helped buy the vaccines that were in the rich world but not getting to the poor kids, getting a very cheap price and figuring out the cold chain, getting the delivery right, and then funding research for new vaccines. A lot of them are coming along. We've got a meningitis vaccine out, got that through large parts of Africa. That has been a huge success.

Sometimes we do get taken by surprise. For example, when the Internet came along, we had it as a fifth or sixth 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.

Often you have to rely on intuition.

Living on $6 a day means you have a refrigerator, a TV, a cell phone, your children can go to school. That's not possible on $1 a day.

Inspiration starts somewhere.