"Racism, pollution and the rest of it are themselves very close to extinction."

"Sometimes I think we're alone. Sometimes I think we're not. In either case, the thought is staggering."

"Humanity is acquiring all the right technology for all the wrong reasons."

"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong."

"Either war is obsolete or men are."

"Now there is one outstandingly important fact regarding Spaceship Earth, and that is that no instruction book came with it."

"The Way is harshness greeted with kindness, fear greeted with fortitude."

"Time is but the stream I go a-fishing in. I drink at it but as I drink, I see the sandy bottom and detect how shallow it is."

"To avoid criticism, do nothing, say nothing, and be nothing."

"Four things come not back -- the spoken word, the sped arrow, the past life, and the neglected opportunity."

"An enormous part of our mature experience cannot not be expressed in words."

"The greatest giver of alms is cowardice."