At some time around 200 A.D., the Stoic philosopher and teacher Cleomedes delivered a set of lectures on elementary astronomy as part of a complete introduction to Stoicism for his students. The result was The Heavens (Caelestia), the only work by a professional Stoic teacher to survive intact from the first two centuries A.D., and a rare example of the interaction between science and philosophy in late antiquity. This volume contains a clear...