No matter how hard it seems just keep going, don't quit because we only fail when we give up.

The belief that the world is getting worse, that we can't solve extreme poverty and disease, isn't just mistaken. It is harmful.

Fame means millions of people have the wrong idea of who you are.

I believe there are no questions that science can't answer about a physical universe.

Lightly and naturally, in this crazy maelstrom of energy and movement, he seemed to glide over the tops of huge boulders.

Motivation is what gets you started. Habit is what keeps you going.

“Nobody made a greater mistake than he who did nothing because he could do only a little.”