The bestselling philosopher's unforgettable exploration of the true meaning of life on earth, now in paperback for the first time.   What is the purpose of life on earth? In An Unknown World, philosopher Jacob Needleman frames man's role on the planet in a completely new and fresh way, moving beyond the usual environmental concerns to reveal how the care and maintenance of a world is something vital and basic to our existence as authentic human beings. "Striking . . . takes some really original positions on topics that have become run into the ground by the same discussions and same assumptions." --Ken Wilbur "His lively prose, storytelling skills and lucid insights draw us into an animated conversation with a brilliant teacher." --Publishers Weekly