Bears: When you see a bear, the spot where you see it becomes instantly different from every place else you've seen. Bears make you pay attention. They keep the mountains from turning into a blur. . . . A woods with a bear in it is real to a man walking through it in a way that a woods with no bear is not. Roscoe Black, a man who survived a serious attack by a grizzly in Glacier National Park some years ago, described the moment when the bear had him on the ground: "He lay on me for a few seconds, not doing anything. . . . I could feel his heart beating against my heart." The idea of that heart beating someplace just the other side of ours is what makes people read about bears and tell stories about bears and theorize about bears and argue about bears and dream about bears. Bears are one of the places in the world where big mysteries run close to the surface.