Wallace's sales agent, back in London, heard mutterings from some naturalists that young Mr. Wallace ought to quit theorizing and stick to gathering facts. Besides expressing their condescension toward him in particular, that criticism also reflected a common attitude that fact-gathering, not theory, was the proper business of all naturalists.

But private lands development around the periphery of the parks - Grand Teton and Yellowstone - is a crucial issue because if those private lands are transformed from open pastures, meadow, forest land to suburbs, to little ranchettes, to shopping malls, to roads, to Starbucks - if those places are all settled for the benefit of humans, then the elk are not going to be able to migrate in and out of Yellowstone Park anymore. And if the elk can't migrate into the park, then that creates problems for the wolves, for the grizzlies, for a lot of other creatures.

If you're Maasai Mara National Park in Kenya, if you're in Serengeti National Park in Tanzania, you don't get out of your vehicle and go walking around amid the lions and the leopards. You stay in your Land Rover. You stay in your safari van, and you look out the windows or you look out the pop top at these animals. I know by experience how badly that can work out if you violate those guidelines.

I used to read only fiction. Now I don't read much, only occasionally, such as a Cormac McCarthy or a Jim Harrison novel.

What do we measure when we measure time? The gloomy answer from Hawking, one of our most implacably cheerful scientists, is that we measure entropy. We measure changes and those changes are all for the worse. We measure increasing disorder. Life is hard, says science, and constancy is the greatest of miracles.

Among the earliest forms of human self-awareness was the awareness of being meat.

I wrote four novels, but then I realized that the world didn't need me to be a novelist, but the world could use me as a nonfiction writer.