Fleeing a failed marriage and haunted by ghosts of his past, Luis Alberto Urrea jumped into his car and headed west. Driving cross-country with a cat named Rest Stop, Urrea wandered the West from one year's spring through the next. Hiking into aspen forests where leaves "shiver and tinkle like bells" and poking alongside creeks in the Rockies, he sought solace and wisdom. In the forested mountains he learned not only the names of trees--he learned...