It is good to be reminded that ""explorers"" still exist, and that there are still places left to explore. In 1994, Tibetan scholar Peissel (The Lost World of Quintana-Roo) joined an expedition deep into Tibet in search of the source of the Mekong River. (The Royal Geographical Society later proclaimed the successful trip ""one of the last great geographical mysteries of the world solved."") Here, Peissel delivers an absorbing tale enriched by his detailed understanding of a mysterious land and by his obvious admiration and love of its people. Included are the daily routines and hardships of the trip, an anthropological look at Tibetan culture and a healthy dose of natural science. Peissel also offers an abundance of personal ruminations. Comparing the modern lives of Westerners to those of Tibetans, he writes, ""For years I had wondered what we were made for. Were we made for comfort or discomfort, for hardship or for pleasure?"" Peissel, it seems, was made for adventure--and to bring those adventures back as a book to please armchair explorers everywhere. Map and eight pages of color photos not seen by PW. (Dec.) FYI: Peissel's expedition is the subject of a fall 1997 A&E special, Smithsonian Expeditions: The Source of the Mekong.