American government is not dominated by engineers, it is dominated by lawyers. Engineers are interested in substance and building things; lawyers are interested in process and rights and getting the ideology correctly blended. And so there is sort of no really concrete plan for the future.

The debt austerity would not be problems if we had technological progress. If you doubled the debt in the U.S., and the size of the economy doubled because of technological progress and growth, the two would roughly cancel out and it would all be a totally manageable situation.

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

I do think Bitcoin is the first [encrypted money] that has the potential to do something like change the world.

People working on bigger ideas on a more protracted timeline will be more on the stealth side. They aren’t releasing new PR announcements every day. The bigger the secret and the likelier it is that you alone have it, the more time you have to execute. There may be far more people going after hard secrets than we think.

All happy companies are different: each one earns a monopoly by solving a unique problem. All failed companies are the same: they failed to escape competition.

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.