Knowing human essential self, namely who-ness and what-ness of the self, has been one of  scholar`s, concern, particularly muslim`s under such titles as knowledge of the soul or knowledge of the self. Mowlavi has met meaningfully the subject with his own ontological and epistemological principles in a mystical approach. As he says, one never can know his essential self in the shadow of common experiments. Rather, such a knowledge would be possible only by mystical experience and by leaving conceptual knowledge. On mystical approach, therefore, real knowledge of the self may be found in leaving the self; when all distinctions between the subject and object disappear and, therefore, human will and awareness and reason all become united in a higher being. In such a position, one arrive at knowledge of the self and knowledge of God. The position is mystically called disappearing in God.