This dictionary is the first to anatomize the philosophical tradition and to show the thoughts, paradoxes, errors and breakthroughs that underlie human speculation. Organized alphabetically by philosopher, and comprehensively indexed by thought and concept, it enables readers to discover who said what, and what was said by whom. More than three hundred philosophers are represented, from Aristotle to Zeno, among them Aquinas, De Beauvoir, Einstein and Sartre, and the quotations range from short, cryptic phrases to lengthy statements.