Through network diagrams and sustained narrative, Randall Collins traces the development of philosophical thought in China, Japan, India, ancient Greece, the medieval Islamic and Jewish world, medieval Christendom, and modern Europe. What emerges from this history is a general theory of intellectual life, one that avoids both the reduction of ideas to the influences of society at large and the purely contingent local construction of meanings. Instead, Collins focuses on the social locations where sophisticated ideas are formed: the patterns of intellectual networks and their inner divisions and conflicts. According to his theory, when the material bases of intellectual life shift with the rise and fall of religions, educational systems, and publishing markets, opportunities open for some networks to expand while others shrink and close down. It locates individuals -- among them celebrated thinkers like Socrates, Aristotle, Chu Hsi, Shankara, Wirt Henstein, and Heidegger -- within these networks and explains the emotional and symbolic processes that, by forming coalitions within the mind, ultimately bring about original and historically successful ideas.