In man, at least, satisfaction is commonly followed by boredom.

Human destiny is bound to remain a gamble, because at some unpredictable time and in some unforeseeable manner nature will strike back.

Think globally, act locally": "Our salvation depends upon our ability to create a religion of nature.

Biologically, man is still the great amateur of the animal kingdom; he is unique in his lack of anatomical and physiological specialization.

Man not only survives and functions in his environment, he shapes it and he is shaped by it.

Human diversity makes tolerance more than a virtue; it makes it a requirement for survival.

Social evolution may be the result of intention, but it rarely, if ever, produces the result intended.