Most people who decide to take the mule ride through the Grand Canyon focus on the spectacular beauty around them. Donald Davis, however, found his focus trained sharply on the 48-inch-wide trail whose ledge drops 700 feet to the Colorado River. Interweaving his trademark humor with vivid detail of perhaps the most remarkable experience offered by the National Park Service, Davis paints for us the stages of this adventure: the gleeful anticipation, the encounter with his own personal mule, the ....