Transubstantial Motion is a thought-provoking analysis of Mulla Sadras innovative theory of transubstantial motion. Expounding on Sadras theory and critique of earlier philosophers, Mahdi Dehbashi explains how the theory of transubstantial motion bridged the physical and spiritual aspects of reality and how Sadra solved the philosophical dilemmas of his era. Also included is a translation of the chapters of al-Asfar al-Arbaah (The Four Spiritual Journeys) in which Mulla Sadra presents his theory and takes the reader through a rewarding discourse on the nature of space and time a discourse only fully appreciated in the light of modern physics. In addition to discussing the physical universe, this work provides a new philosophical base for Islamic metaphysics, eschatology, ethics, and the philosophy of the human soul.