But the amazing thing is this: over the years, the experience has occurred again and again, to mountaineers, divers, polar explorers, prisoners of war, solo sailors, aviators, astronauts and 9/11 survivors. All have escaped traumatic events only to tell strikingly similar stories of having experienced the close presence of a helper or guardian. The mysterious force has been explained as everything from hallucination to divine intervention. Recent neurological research suggests something else. New paperback.