Visualize yourself confronted with the task of killing, one after the other, a cabbage, a fly, a fish, a lizard, a guinea pig, a cat, a dog, a monkey and a baby chimpanzee. In the unlikely case that you should experience no greater inhibitions in killing the chimpanzee than in destroying the cabbage or the fly, my advice to you is to commit suicide at your earliest possible convenience, because you are a weird monstrosity and a public danger.

Barking dogs may occasionally bite, but laughing men hardly ever shoot!

There is no faith which has never yet been broken, except that of a truly faithful dog

Truth in science can be defined as the working hypothesis best suited to open the way to the next better one.

I am convinced that of all the people on the two sides of the great curtain, the space pilots are the least likely to hate each other. Like the late Erich von Holst, I believe that the tremendous and otherwise not quite explicable public interest in space flight arises from the subconscious realization that it helps to preserve peace. May it continue to do so!

Just thinking that my dog loves me more than I love him, I feel shame.

Man has been driven out of the paradise in which he could trust his instincts.