In this episode of pplpod, we explore the life and ideas of Anaximenes (c. 586–526 BC), the last of the three great philosophers of the Milesian School. We discuss how Anaximenes reconciled the theories of his predecessors, Thales and Anaximander, by proposing that the arche—the fundamental substance of the universe—is air.

Join us as we break down Anaximenes’s revolutionary contribution to early science: a physical explanation for how matter changes form. We explain his theory of rarefaction and condensation, a process where air thins to become fire or condenses to become wind, water, and stone. We also look at his unique cosmology, which envisioned a flat Earth floating on air like a leaf, and his theory that the human soul is composed of the same "breath" that holds the universe together.