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.

Hands-on experience at the critical time, not systematic knowledge, is what counts in the making of a naturalist. Better to be an untutored savage for a while, not to know the names or anatomical detail. Better to spend stretches of time just searching and dreaming.

Let us see how high we can fly before the sun melts the wax in our wings.

The living environment is the biosphere, the thin layer around the world of living organisms. We're part of that. Our existence is dependent on it in ways that people haven't even begun to appreciate. Our existence depends not just on its existence, but its stability and its richness.

Every native species, however humble in appearance...has its place in the nation's heritage. It is a masterpiece of evolution, an ancient, multifaceted entity that shares the land with us.

If insemination were the sole biological function of sex, it could be achieved far more economically in a few seconds of mounting and insertion. Indeed, the least social of mammals mate with scarcely more ceremony. The species that have evolved long-term bonds are also, by and large, the ones that rely on elaborate courtship rituals. . . . Love and sex do indeed go together.

Humanity, in the desperate attempt to fit 8 billion or more people on the planet and give them a higher standard of living, is at risk of pushing the rest of life off the globe.