An inquiry into the human prospect : with "Second thoughts" and "what has posterity ever done for me?" / Robert L. Heilbroner. Heilbroner, Robert L. Civilization, Modern 1950- Regression (Civilization) CB428 .H44 1975 901.9 HEI Includes bibliographical references and index. New York : Norton, c1975. c1975. 1975 Text 180 p. ; eng