 The heavenly bodies are not only immaterial for Avempace and the long Aristotelian tradition, but they are also the most spiritual and are followed in rank by the class of the active intellect and the acquired intellect. The active intellect is immaterial, but the acquired intellect has some connection to matter “because it perfects (mutammim) the material intelligibles” (IB-RS-AP: 19. 10; IB-coll-genequand: 133 §59: “il actualize”). The latter are “not spiritual per se because their existence takes place in prime matter” (IB-RS-AP: 19. 7–8; IB-coll-genequand: 132 §59), and we assume that they are the internal counterpart of the substantial forms. We see that spiritual forms differ from similar forms which are joined to matter and determine the substances.