A Lesson from the Arcane World of the Heavenly Spheres According to Maimonides

So that the ordinary Jew have an informed view of creation as a step toward true conviction about God, Maimonides devotes chapter three of "Hillscot yesode hattoriih" of the Mifoe Torah to an exposition of medieval astrophysics. The system he expounds has several traits that are strange to modern ears: first, it is geocentric; second, the heavenly bodies do not move by themselves in space but are embedded in transparent spheres which move; third, there is no empty space at all between these spheres; and fourth, Aristotelian physics demanded a system with circular uniform movement about a single fixed center. However, since the actually observed motions of the heavenly bodies do not fit this model, ancient and medieval astrophysicists invented a complicated series of spheres-within-spheres to account for the actual phenomena. This attempt to "save the phenomena," as Simplicius put it, seems very artificial to us, particularly since we now know it to have been a useless undertaking. We reject geocentrism, we accept the idea of space, and we are not bound by the idealist definitions of motion in Aristotelian physics. Maimonides, however, accepted all this and, as we shall see, took an important place in the extended fight over which of the explanations available to him was the correct one. 1