“I think when you begin to think of yourself as having achieved something, then there's nothing left for you to work towards. I want to believe that there is a mountain so high that I will spend my entire life striving to reach the top of it.”

“When your reasons for believing something are justified ad hoc, you are left susceptible to further discoveries undermining the rationale for that belief.”

“We spend the first year of a child's life teaching it to walk and talk and the rest of its life to shut up and sit down. There's something wrong there.”

“Your journey has molded you for your greater good, and it was exactly what it needed to be. Don't think you've lost time. There is no short-cutting to life. It took each and every situation you have encountered to bring you to the now. And now is right on time.”

“I know that the molecules in my body are traceable to phenomena in the cosmos. That makes me want to grab people on the street and say: ‘Have you HEARD THIS?”

“Some morning while your eating breakfast and you need something new to think about, though, you might want to ponder the fact that you see your kids across the table not as they are but as they once were, about three nanoseconds ago.”

“Robots are important also. If I don my pure-scientist hat, I would say just send robots; I'll stay down here and get the data. But nobody's ever given a parade for a robot. Nobody's ever named a high school after a robot. So when I don my public-educator hat, I have to recognize the elements of exploration that excite people. It's not only the discoveries and the beautiful photos that come down from the heavens; it's the vicarious participation in discovery itself.”