Heat, Pneuma, and Soul in Ancient Philosophy and Science
Reece discusses Diogenes of Apollonia’s claim that “all existing things are differentiated from the same thing and are the same thing” (DK 64B2, Simp. Phys. 151.31–32), namely air. He examines Diogenes’ principle that causal interaction and change require some sort of uniformity among the relata, and considers the questions which this principle raises.