Diogenes of Apollonia was a Greek philosopher belonging to the last generation of the pre-Socratics (fl. around 440–430 BCE.) His native town was either Apollonia on Crete or, more probably, Apollonia on the Pontus. Nothing is known for certain about his life. It has been debated whether he wrote only one book called, in English, On Nature or, as Simplicius reported (in On Aristotle's "Physics" 151, 20), four (On Nature, Meteorology, On the Nature of Man, Against the Sophists). All the existing fragments seem to come from On Nature. His work had an effect in Athenian intellectual life toward the end of the fifth century BCE, and his influence is detectable also in some treatises of the Hippocratic corpus and in the Stoic doctrine of pneuma (literally breath; in Stoic philosophy, the mixture of the two active elements, fire and air...