ABSTRACT
Mulla Sadra's concept of substantial motion represents a major departure from the Peripatetic concept of change, and lends itself to a set of new possibilities in traditional Islamic philosophy and cosmology. This chapter analyses the substantial motion and the ways in which Sadra incorporates and reformulates the traditional notions of qualitative and quantitative change in his natural philosophy. Following the scheme of Aristotelian physics, Sadra begins his discussion of motion by explaining the meaning of potentiality. Sadra goes on to adduce proofs for the necessity of a prime mover as an external agent to set things in motion. There are two possible ways for a mover to set things in motion: It moves things either directly and by itself or indirectly and by means of something else. Sadra's overall reply to these claims is that in some cases, as in the relationship between sperm and man, potentiality precedes actuality in time.
