The lowest-hanging fruit in preventative medicine is just to really focus on nutrition.

Forget startup companies. The next frontier is startup countries.

It is sort of a bit of a caricature of capitalism, that it's always this zero-sum game where you have winners and losers. Silicon Valley, the technology industry at its best, creates a situation where everybody can be a winner.

I think in my twenties I tended to think of all people as sort of more or less alike. In now think that people are really different in all these subtle ways that are very important.

I'm in favor of free trade, but I think if you had to make a choice between having technological progress versus free trade, you had one or the other, you should always pick technological progress. I think it's an incredibly important variable for creating more prosperity.

If you think your initial market might be too big, it almost certainly is.

Twitter is hard to evaluate. They have a lot of potential. It's a horribly mismanaged company — probably a lot of pot-smoking going on there. But it's such a solid franchise it may even work with all that.