Donald D. Clayton is a nuclear astrophysicist who's committed to those ""beautiful intellectual structures of the human mind"" devised by such men as the architects of Stonehenge, Copernicus, Kepler, Newton and Einstein. His title reflects an inspirational moment when, as a Caltech grad student visiting the wide open spaces of west Texas, he looked up into the galaxies, ""made an emotional contact with my scientific life,"" and decided for a career exploring the teasers and mind-benders of cosmology and astronomy. One of his heroes is Jean-Philippe Loys de Cheseaux, an 18th century scholar who had the insight to ask simple questions like ""why is the night sky dark?"" and found an answer by measuring the distances between fixed stars. Ernest Rutherford's question--why don't radioactive elements disappear entirely?--led to his discovery of a ""cosmic dock."" There's also discussion of ""the Big Bang,"" Hubble's Proof that the universe is expanding and Sir Fred Hoyle's ""steady-state theory"" not to mention the fascination of Stanley Kubrick's 2001. Above all, this is a sweeping view of scientific inquiry as the greatest human adventure. Justified for the informed layman.