I watched the piles of feces go up the conveyor belt... They made their way through the machine... A few minutes later I took a long taste of the end result: a glass of delicious drinking water.

I get more spam than anyone I know.

When I say "an energy miracle," I mean that there will be some form of energy whose 24 hour cost really is competitive with hydrocarbons given, say, 20 years of learning curve. You invent it, then you look at how much its costs go down over the next 20 years, that it really beats hydrocarbons.

If something's expensive to develop, and somebody's not going to get paid, it won't get developed. So you decide: Do you want software to be written, or not?

If you think of global public goods like polio eradication, the kind of risk-taking new approach, philanthropy really does have a role to play there, because government doesn't do R&D about new things naturally as much as it probably should, and so philanthropy's there.

Leaders are those who empower others.

I'm a great believer that any tool that enhances communication has profound effects in terms of how people can learn from each other, and how they can achieve the kind of freedoms that they're interested in.