It's OK for China to invent cancer drugs that cure patients in the United States. We want them to catch up. But as the leader, we want to keep setting a very, very high standard. We don't want them to catch up because we're slowing down or, even worse, going into reverse.

It's hard to improve public education - that's clear.

We all have the chance to create a world where extreme poverty is the exception rather than the rule.

I agree with people like Richard Dawkins that mankind felt the need for creation myths. Before we really began to understand disease and the weather and things like that, we sought false explanations for them. Now science has filled in some of the realm – not all – that religion used to fill.

I never took a day off in my twenties. Not one. And I'm still fanatical, but now I'm a little less fanatical.

You might say, well, aren't people saying that about wind and solar today? Not really. Only in the super-narrow sense that the capital costs per output, when the wind is blowing, is slightly lower.

It's the poorer people in tropical zones who will get really hit by climate change - as well as some ecosystems, which nobody wants to see disappear.