This social-networking thing takes you to crazy places.

The only role other than paying their taxes, whatever those are, the only role for philanthropy broadly - of which the rich should give disproportionately - the more, the better - and I think there is a positive trend in that direction - there are certain risk-taking things, like trying out a new type of charter school or funding a new kind of medicine.

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

The quality of research in the U.S. is absolutely the best.

I think given all the different imperatives - getting energy to Africa, security of energy, climate change, that we should be spending half as much as we spend on health, which will get you all the way up to $15 billion - the health people don't like it when things get compared to their number.

Don’t tax my income, tax my consumption.

You're never going to get the amount of CO2 emitted to go down unless you deal with the one magic metric, which is CO2 per kilowatt-hour.