The Western tradition of philosophy began in Greece with a cluster of thinkers often called the Presocratics, whose influence has been incalculable. They include the early Ionian cosmologists, Pythagoras, Heraclitus, the Eleatics (Parmenides, Melissus, and Zeno), Empedocles, Anaxagoras, the atomists and the sophists. All these thinkers are discussed in this volume both as individuals and collectively in chapters on rational theology, epistemology, psychology, rhetoric and relativism, justice, and poetics. A chapter on causality extends the focus to include historians and medical writers.