"Each new page [is] more spellbinding than the one before--this is surely one of the most interesting books I've ever read."--Elizabeth Marshall Thomas, author of The Hidden Life of Dogs When Bernd Heinrich decided to write a memoir of his ultramarathon running experience he realized that the preparation for the race was as important, if not more so, than the race itself. Considering the physiology and motivation of running from a scientific point of view, he wondered what he could learn from other animals. With his characteristic blend of scientific inquiry and philosophical musings, Heinrich offers an original and provocative work combining the rigors of science with the passion of running.