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

To the desert go profits and hermits, through deserts go pilgrims and exiles. Here the leaders of the great religions have sought the therapeutic and spiritual values of retreat, not to escape but to find reality.

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

All around us, aspects of the modern world - diet, exercise, medicine, art, work, family, philosophy, economics, ecology, psychology - have begun a long circle back toward their former coherence. Whether they can arrive before the natural world is damaged beyond repair and madness destroys humanity, we cannot tell.

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

Careless of waste, wallowing in refuse, exterminating the enemies . . . despising age, denying human natural history, fabricating pseudotraditions, swamped in the repeated personal crises of the aging preadolescent; all are familiar images of American society. They are signs of private nightmares of incoherence and disorder in broken climaxes where technologies in pursuit of mastery create ever-worsening problems - private nightmares expanded to a social level.

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.