Classical Age
In the fifth century BCE Diogenes of Apollonia revived and extended the Ionian tradition of natural philosophy, teaching that air is the single underlying substance of the cosmos and, being infused with intelligence, the divine principle that orders and gives life to all things. Drawing together strands from Anaximenes and Anaxagoras, his account of the unity and purposeful arrangement of nature was well enough known to be parodied by Aristophanes in Athens—and it marks one of the last flowerings of Presocratic cosmology before philosophy turned toward Socrates and human affairs.