(discuss equants, deferents and epicycles, using the non-uniform motion of the Moon, and the motions responsible for the Saros)

(NOTE TO SELF: As shown here, the next topic is Seasons. Could take care of that, and then come back to orbits later, but seems more appropriate to, as in most texts, finish with orbital motions, then take care of remaining sky motions and effects -- day/night, seasons, precession, etc -- later on.)