The origins of Stoic proof of the existence of God

A virtually scriptural text for early Stoic theology was Xenophon, Memorabilia 1.4. It contains the earliest known specimen of the Argument from Design and is an invaluable and under-appreciated source on Socrates' theology, and its ideas should not, as they often have been, be assumed to be derived from anyone else, least of all from Diogenes of Apollonia, whose contribution to the history of teleological thought has been greatly exaggerated. In Sextus Empiricus, Adversus Mathematicos 9.88-110 we have, I argue, a uniquely revealing source : it shows the first generation of Stoics vying to extract the best formal theological argument from that Xenophon chapter; similarly extracting a formal theological argument from Plato, Timaeus 29b-30b; and adjusting the resultant syllogisms so as to minimize their vulnerability to the parodic attacks (parabolai) of their contemporary critic Alexinus. The upshot is a unique opportunity to watch the early Stoics at work, forging their own arsenal from the classical tradition whose heirs they considered themselves to be.