The natural world is not only a set of constraints but of contexts within which we can more fully realize our dreams.

The human cardiovascular system evolved as part of the physiology of [prehistoric] hunters, who ran for their lives.

The desert sky is encircling, majestic, terrible.

When men do not run they are likely to die prematurely from dysfunction of the heart and vascular systems or from disabling chronic disease.

Men are born human. What they must learn is to be an animal. If they learn otherwise it may kill them, and kill life on the planet.

There is a secret person undamaged in every individual.

Who would want to live in a world that is just not quite fatal?