“Doubt is the thing that’ll kill you, the only thing, and it’ll kill your friends, too.”

“Your enemies can kill you, but only your friends can hurt you.”

“All men kill the thing they hate, too, unless, of course, it kills them first.”

“To my mind, the only possible pet is a cow. Cows love you. They will listen to your problems and never ask a thing in return. They will be your friends forever. And when you get tired of them, you can kill and eat them. Perfect.”

“...if you always put limits on what you can do, physical or anything else, it’ll spread over into the rest of your life. It’ll spread into your work, into your morality, into your entire being. There are no limits. There are plateaus, but you must not stay there, you must go beyond them. If it kills you, it kills you. A man must constantly exceed his level.”

“It's very strange to be an imaginary friend. You can't be suffocated and you can't get sick and you can't fall and break your head and you can't catch pneumonia. The only thing that can kill you is a person not believing in you.”