The way soul and body are related to each other gives rise to the issue of relation between soul and body or dualism, which is now taken to be a serious concern in the philosophy of mind. No Western philosopher has thus far succeeded in giving a persuasive answer to this problem. Mulla Sadra, however, in the world of Islam, was able to give an unprecedented account of issues related to soul after presenting new philosophical foundations, including priority of existence, trans-substantial motion and gradation in existence. According to him, soul has, in the beginning, takes a physical form with the body as its lower stage, but it reaches other stages through a mode of trans-substantial motion. Basind his arguments on the doctrine of the soul’s corporeal createdness and its tras-substantial motion, he believes that the relation between soul and body is a unifying relationship and that man has a reality of various degrees accordingly. Given these facts, he goes on to explain how soul and body interact.