Presocratic

Presocratic |ˌpriːsəˈkratɪk | ▶adjective relating to or denoting the speculative philosophers active in the ancient Greek world in the 6th and 5th centuries bc (before the time of Socrates ), who attempted to find rational explanations for natural phenomena. They included Parmenides, Anaxagoras, Empedocles, and Heraclitus. ▶noun a Presocratic philosopher.