I believe-and human psychologists, particularly psychoanalysts should test this-that present-day civilized man suffers from insufficient discharge of his aggressive drive. It is more than probable that the evil effects of the human aggressive drives, explained by Sigmund Freud as the results of a special death wish, simply derive from the fact that in prehistoric times intra-specific selection bred into man a measure of aggression drive for which in the social order today he finds no adequate outlet.

I have found the missing link between the higher ape and civilized man; it is we.

The fidelity of a dog is a precious gift demanding no less binding moral responsibilities than the friendship of a human being.

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.

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

Evil, by definition, is that which endangers the good, and the good is that which we perceive as a value.

...he who has seen the intimate beauty of nature cannot tear himself away from it again. He must become either a poet or a naturalist and, if his eyes are keen and his powers of observation sharp enough, he may well become both.