While John McPhee was working on his previous book, Rising from the Plains, he happened to walk by the engineering building at the University of Wyoming, where words etched in limestone said: "Strive on--the control of Nature is won, not given." In the morning sunlight, that central phrase--"the control of nature"--seemed to sparkle with unintended ambiguity. Bilateral, symmetrical, it could with equal speed travel in opposite directions...