The doctrine of “reality and tenuity” is a demonstrative-mystical one which has been grasped by Mullā Sadrā through an interdisciplinary approach and speculation over key passages of scripture and has been used then for exegesis of all scriptures. Using this doctrine, he has been able to present an authorized understanding of the issues in philosophical theology and rational cosmology without falling into either mere transcendence or sheer similarity. According to this doctrine, there are at least two major stages of beings: Reality as Sovereignty and tenuity as descent from the former stage. This doctrine, which is analogous to gradation in manifestations, considers the reality to be descended in the stages of tenuity. Thus, according to this doctrine, there is a unity of reality in all stages of existence and individual Oneness of Being. Hence, the pure existence manifests itself in the world of Divine Names and then descends from world to world. So, there are some passages of scripture which could not be interpreted without taking this doctrine to be granted. These passages are those which include some beliefs such as Firstness and Lastness of God, the unity of His outwardness and inwardness, coexistence of God and creatures while being necessary, descent of beings from the hidden Divine realm, and the influence of Divine Names on existence of beings and the emanation of existence.
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