It is not man the ecological crisis threatens to destroy but the quality of human life.

... men as a rule are more preoccupied with the dangers that threaten their life than interested in the biological forces on which they depend for a constructive existence.

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

As long as mankind is made up of independent individuals with free will, there cannot be any social status quo. Men will develop new urges, and these will give rise to new problems, which will require ever new solutions. Human life implies adventure, and there is no adventure without struggles and dangers.

The belief that we can manage the Earth and improve on Nature is probably the ultimate expression of human conceit, but it has deep roots in the past and is almost universal.

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

Nature always strikes back. It takes all the running we can do to remain in the same place.