To drown a river beneath its own impounded water, by damming, is to kill what it was and to settle for something else. When the damming happens without good reason . . . then it's a tragedy of diminishment for the whole planet, a loss of one more wild thing, leaving Earth just a little flatter and tamer and simpler and uglier than before.

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.

[Theory is] an explanation that has been confirmed to such a degree, by observation and experiment, that knowledgeable experts accept it as fact. That's what scientists mean when they talk about a theory: not a dreamy and unreliable speculation, but an explanatory statement that fits the evidence. They embrace such an explanation confidently but provisionally - taking it as their best available view of reality, at least unil some severely conflicting data or some better explanation might come along.

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.

Evolution as described by Charles Darwin is an scientific theory, abundantly reconfirmed, explaining physical phenomena by physical causes. Intelligent Design is a faith-based initiative in rhetorical argument. Should we teach I.D. in America's public schools? Yes, let's do - not as science, but alongside other spiritual beliefs, such as Islam, Zoroastrianism and the Hindu Idea that Earth rests on Chukwa, the giant turtle.

Of course anyone who truly loves books buys more of them than he or she can hope to read in one fleeting lifetime. A good book, resting unopened in its slot on a shelf, full of majestic potentiality, is the most comforting sort of intellectual wallpaper.

Kill off the sacred bear. Kill off the ancestral crocodile. Kill off the myth-wrapped tiger. Kill off the lion. You haven't conquered a people, or their place, until you've exterminated their resident monsters.