“Big breakthroughs happen when what is suddenly possible meets what is desperately needed”

“Every morning in Africa, a gazelle wakes up. It knows it must run faster than the fastest lion, or it will be killed. Every morning a lion wakes up. It knows it must outrun the slowest gazelle, or it will starve to death. It doesn't matter whether you are a lion or a gazelle. When the sun comes up, you better start running.”

“So what am I? I guess I would call myself a sober optimist...If you are not sober about the scale of the challenge, then you are not paying attention. But if you are not an optimist, you have no chance of generating the kind of mass movement needed to achieve the needed scale.”

“When widely followed public figures feel free to say anything, without any fact-checking, it becomes impossible for a democracy to think intelligently about big issues.”

“Pessimists are usually right and optimists are usually wrong but all the great changes have been accomplished by optimists.”

“That's right-the striking thing about greenhouse gases is the diversity of sources that emit them. A herd of cattle belching can be worse than highway full of hummers.”

“The saying in China is "If you're one in a million, there's still 1,300 people just like you.”