pre-Socratic philosophy

The ideas of the usually speculative ancient Greek cosmologists who mainly preceded Socrates (469–399 BC). The pre-Socratics range from Thales (640–546 BC) to Democritus (c. 460–361 BC). The school is defined more by an outlook and a range of interests than by any chronological limit. Unlike Socrates and the sophists, who were both primarily concerned with ethics and politics, the pre-Socratics were mainly concerned with the search for universal principles to explain the whole of nature, its origin, and human destiny.

Other pre-Socratics are Pythagoras, Xenophanes, Parmenides, Zeno of Elea, Anaximander, Empedocles, Heraclitus, Diogenes, and Protagoras. Only short passages from the works of the pre-Socratic philosophers have survived.