Ephesian school sometimes refers to the philosophical thought of the ancient Greek philosopher Heraclitus of Ephesus, who considered that the being of all the universe is fire. According to him, the being is material and one, but at the same time he acknowledges that the world witnesses constant change. Motion of the archelement (fire) is discordant and unharmonious, even though harmony is the final result of the process.

Although there was never an official "Ephesian School," Diogenes Laërtius (ix. 6) mentions that his philosophy did have followers who called themselves "Heracliteans." Plato portrays Cratylus in his dialogue of the same name as a disciple of Heraclitus.