Be like a postage stamp. Stick to one thing until you get there.

It's not only the most difficult thing to know one's self, but the most inconvenient.

I haven't got as much money as some folks, but I've got as much impudence as any of them, and that's the next thing to money.

Every man has his follies - and often they are the most interesting thing he has got.

Experience is one thing you can't get for nothing.

Right now, what we know about Pluto could be written on the back of a postage stamp. After this mission, we'll be able to fill textbooks.