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.

The human mind, in taking us down the path of technocracy, has become the adversary of life itself and collaterally the adversary of the human soul.

The appeal of the cat lies in the very fact that she has formed no close bond with [man], that she has the uncompromising independence of a tiger or a leopard while she is hunting in his stables and barns: that she still remains mysterious and remote when she is rubbing herself gently against the legs of her mistress or purring contentedly in front of the fire.

Most of the vices and mortal sins condemned today correspond to inclinations that were purely adaptive or at least harmless in primitive man

All scientific knowledge to which man owes his role as master of the world arose from playful activities.

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

It is a good morning exercise for a research scientist to discard a pet hypothesis every day before breakfast. It keeps him young.