Patience is a key element of success.

So not only are we saving lives now, we're creating the incentive for the breakthroughs that over the next generation will mean we can take AIDS, malaria and TB and bring those numbers dramatically down.

Philanthropy should be taking much bigger risks that business. If these are easy problems, business and government can come in and solve them.

I've been studying how quickly we can get energy out to the poor countries - a lot of which are in Africa - and how little progress we've made there. There's no more electricity today in sub-Saharan Africa per person than there was 20 years ago.

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.

Now, if you're rich, you can spend a lot of money, Netherlands-style, and reduce that. But Bangladesh or parts of India, like Calcutta, they just simply won't be able to afford that kind of protection.

Nobody has a guaranteed position in computer technologies business. We've done some good work, but all of these products become obsolete so fast and the structure of the business as it broadens out is going to be so different.