Pre-Socratic philosophy, also known as Early Greek Philosophy, is ancient Greek philosophy before Socrates. Pre-Socratic philosophers were mostly interested in cosmology, the beginning and the substance of the universe, but the inquiries of these early philosophers spanned the workings of the natural world as well as human society, ethics, and religion. They sought explanations based on natural law rather than the actions of gods. Their work and writing has been almost entirely lost. Knowledge of their views comes from testimonia, i.e. later authors' discussions of the work of pre-Socratics. Philosophy found fertile ground in the ancient Greek world because of the close ties with neighboring civilizations and the rise of autonomous civil entities, poleis.
Pythagoras
Parmenides
Heraclitus
St. Elmo's fire (luminous plasma created by a corona discharge from a rod-like object) in a ship. Xenophanes' contemporaries attributed this phenomenon to the deity Dioscuri. Xenophanes argued that the observed illumination is due to small clouds influenced by special circumstances relating to stars—an example of naturalism and reductionism.
Ancient Greek philosophy arose in the 6th century BC. Philosophy was used to make sense of the world using reason. It dealt with a wide variety of subjects, including astronomy, epistemology, mathematics, political philosophy, ethics, metaphysics, ontology, logic, biology, rhetoric and aesthetics. Greek philosophy continued throughout the Hellenistic period and later evolved into Roman philosophy.
Four Greek philosophers: Socrates, Antisthenes, Chrysippos, Epicurus; British Museum
The philosopher Pyrrho of Elis, in an anecdote taken from Sextus Empiricus' Outlines of Pyrrhonism (upper) PIRRHO • HELIENSIS • PLISTARCHI • FILIVS translation (from Latin): Pyrrho • Greek • Son of Plistarchus (middle) OPORTERE • SAPIENTEM HANC ILLIVS IMITARI SECVRITATEM translation (from Latin): It is right wisdom then that all imitate this security (Pyrrho pointing at a peaceful pig munching his food) (lower) Whoever wants to apply the real wisdom, shall not mind