The difference between a stranger sending you a message that you might be interested in at a very low volume level, no repetition, just sending it to very few people, and that being done as spam - those things get close enough that you want to be careful never to filter out something that's legitimate.

Some people, through luck and skill, end up with a lot of assets. If you're good at kicking a ball, writing software, investing in stocks, it pays extremely well.

We win because we hire the smartest people. We improve our products based on feedback, until they're the best. We have retreats each year where we think about where the world is heading.

Who can afford to do professional work for nothing? What hobbyist can put three man-years into programming, finding all bugs, documenting his product, and distributing it for free?

In K-12, almost everybody goes to local schools. Universities are a bit different because kids actually do pick the university. The bizarre thing, though, is that the merit of university is actually how good the students going in are: the SAT scores of the kids going in.

You know capitalism is this wonderful thing that motivates people, it causes wonderful inventions to be done. But in this area of diseases of the world at large, it's really let us down.

The ideal thing would be to have a 100 percent effective AIDS vaccine. And to have broad usage of that vaccine. That would literally break the epidemic.