  One respect in which al-Kindi follows Alexander is his conviction that the heavenly spheres are the means by which God exercises providence over the sublunary world (see Fazzo and Wiesner 1993).  Al-Kindi’s bold claims for astrology already commit him to the idea that a wide range of specific events can be predicted on the basis of astral causation. His doctrine of providence goes further by implying that all events in the lower world are caused by the stars, which are carrying out the benign “command” of God. This doctrine is set out in On the Prostration of the Outermost Sphere (Abu Rida 1950, 244–261, Rashed and Jolivet 1998, 177–99) and On the Proximate Agent Cause of Generation and Corruption (Abu Rida 1950, 214–237). The former explains that the heavens are possessed of souls, and freely follow God’s command so as to move in such a way that the providentially intended sublunary things and events will come about. This, according to al-Kindi, is what the Koran refers to when it says that the stars “prostrate” themselves before God. In Proximate Agent Cause, meanwhile, al-Kindi gives a more detailed account of the means by which the heavens cause things in the lower world (here he invokes friction, not rays). The most obvious effect of the stars on our world is of course the seasons, because the sun (due to its size and proximity) is the heavenly body with the most powerful effect. If there were no such heavenly causation, according to al-Kindi, the elements would never have combined at all, and the lower realm would consist of four spheres of unmixed earth, water, air and fire.