I regret being the richest man in the world because that position attracts undeserved publicity.

Nigeria has moved into low-middle-income, but their north is very poor, and the health care systems there have broken down.

Polio's pretty special because once you get an eradication, you no longer have to spend money on it; it's just there as a gift for the rest of time.

Online education is pretty special for two reasons. One is that you can get the very best lecture in the world and wherever you are, whenever you want, you can connect to that lecture. The other is this interactivity, where if you know a topic, you can kind of skip over it. Or if you're confused about it, [the area] where you're confused can be analyzed by software.

Never before in history has innovation offered promise of so much to so many in so short a time.

If we [the USA] don't innovate in education, it's literally going to mean less people get to go have that education at a time when more people are going to want it. We've got to put courses out on the Web, we've got to put interactive learning out on the Web.

In the next 15 years, we can halve childhood deaths. That's doable.