This book represents in substance a course of lectures and discussions given first at the University of Illinois and later at Wesleyan University. It was written to meet the needs both of the college student who has the added guidance of an instructor, and of the general reader who has no such assistance. The attempt has been made to keep the presentation simple and clear enough to need no interpreter, and by the list of readings appended to each chapter, to make a self-directed further study of any point easy and alluring. These references arc for the most part to books in English, easily...