How is the rationality of the Stoic god constituted? Commentators often look to the seventeenth-century ‘rationalists’, especially Spinoza, for their inspiration. But the Stoics say that god’s rationality is the same as ours. Since human rationality is defined as a product of concept-acquisition, it may be that the Stoics had to give an ‘empiricist’ account of divine rationality too. Hierocles’ discussion of animal self-perception shows that the Stoics had the conceptual materials for such an account.