The Presocratic philosophers of Ancient Greece were the first philosophers to separate the natural world from the supernatural world. Presocratic thinking dominated philosophical inquiry until about 400 BCE, when a new wave of philosophers including Aristotle and Socrates began focusing more on questions about human life than on questions about the natural world. The Presocratic philosophers who are discussed in this SparkNotes study guide are Thales of Miletus, Anaximander of Miletus, Anaximenes of Miletus, Xenophanes of Colophon, Heraclitus, Parmenides of Elea, the Eleatics (Zeno of Elea and Melissus of Samos), Empedocles, Anaxagoras, and the Atomists (Leucippus and Democritus).

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