The green prehuman earth is the mystery we were chosen to solve, a guide to the birthplace of our spirit, but it is slipping away. The way back seems harder every year. If there is danger in the human trajectory, it is not so much in the survival of our own species as in the fulfillment of the ultimate irony of organic evolution: that in the instant of achieving self-understanding, through the mind of man, life has doomed its most beautiful creations. And thus humanity closes the door on its past.

We don't even know what species are out there, for the most part, particularly when you get down to the microbes and very small invertebrates. They make up the mass of the organisms around us, including the soil we depend on, the soil of cornfields as well as hardwood forests. We haven't taken ecology to the point where we can even make a crude prediction of what's going to happen when we've reduced the living world down to a certain level.

Competing is intense among humans, and within a group, selfish individuals always win. But in contests between groups, groups of altruists always beat groups of selfish individuals.

The one process now going on that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly our descendants are least likely to forgive us.

All three of the Abrahamic religions were born and nurtured in arid, disturbed environments.

Biophilia: the innate pleasure from living abundance and diversity as manifested by the human impulse to imitate Nature with gardens.

Women are extraordinary in lacking the estrus, or period of heat. The females of most other primate species become sexually active, to the point of aggression, only at the time of ovulation. Why has sexual responsiveness become nearly continuous? Unusually frequent sexual activity between males and females served as the principle device for cementing the pair bond.