Going from PayPal, I thought: 'Well, what are some of the other problems that are likely to most affect the future of humanity?' Not from the perspective, 'What's the best way to make money?'

Failure is an option here. If things are not failing, you are not innovating enough.

When something is important enough, you do it even if the odds are not in your favor.

People should pursue what they're passionate about. That will make them happier than pretty much anything else.

I think it is possible for ordinary people to choose to be extraordinary.

I'm extremely confident that solar will be at least a plurality of power, and most likely a majority... in less than 20 years.

Constantly seek criticism. A well thought out critique of what you're doing is as valuable as gold

Optimism, pessimism, f**k that; we're going to make it happen. As God is my bloody witness, I'm hell-bent on making it work.

I think that's the single best piece of advice: constantly think about how you could be doing things better and questioning yourself.

Mars is the only place in the solar system where it's possible for life to become multi-planetarian.

My mentality is that of a samurai. I would rather commit seppuku than fail.

A word can change a mind. A sentence can change a life. A book can change the world.

A philosophy a system of principles that will guide your thoughts and actions.

I've been so lucky to work with such great people: people that are such hard workers and have such a respect and appreciation for one another.

The gap in education in this country, the unfairness of the schools, is one of the great unfairness in this society.

Time has passed through me and become a song.

Leadership is made for service.

That thou remember them, some claim as debt; I think it mercy, if thou wilt forget.

Qigong is a jewel that has many facets.

The collegiate idealists who fill the ranks of the environmental movement seem willing to do absolutely anything to save the biosphere, except take science courses and learn something about it.

In love, such a word, whispered, is a mysterious kiss of the soul to the soul.