There were many diverse schools of thought in Ancient Greek philosophy. Democritus was a pre-socratic philosopher who founded the discipline of Atomism. Anaximander was another pre-socratic thinker who was a member of the Milesian school. Epictetus and Chrysippus were both stoic philosophers. Protagoras was a famous sophist who was referenced by Plato. Heraclides was a Platonist and direct student of Plato. Pythagoras and Theano were both of the Pythagorean school, and are believed to have been married.