enraptured by him. Their desire for God gives rise to the eternal rotary motion of the spheres, which in turn produces the motions we observe in the sublunary world. Like God himself, matter, of which all physical substances are composed, is eternal and uncreated and underlies the eternal process of generation and corruption undergone by things in the sublunary realm. In its large-scale structure the universe has remained unchanged from all eternity. The medieval schoolmen substituted angelic Intelligences