"The greatest danger is not that we aim too high and miss, but that we aim too low and hit."

"I'm doing my best to make sure the future is good."

"Some people use their hair to express themselves. I use Twitter."

"The more rockets we launch, the more likely it is that we'll have a self-sustaining civilization on Mars."

"I think it's important to have a good work-life balance, but I also think it's important to work hard."