When the Dalai Lama of Tibet met with economist John Kenneth Galbraith, he asked the Harvard professor a simple but penetrating question: "What would the world be like if everyone drove a motor car?" The Tibetan leader probably did not intend it, but his question constitutes a koan, a paradoxical riddle of Zen Buddhist tradition. A koan has no logical answer -- "What is the sound of one hand clapping?" -- but the search for a solution may lead to a flash of enlightenment. Seven Wonders: Everyday Things for a Healthier Planetby John C. RyanSierra Club Books, 1999, 128 pages …