definitions of existence and essence that leave the two inextricably linked insofar as humans are concerned, but fundamentally separate insofar as God is concerned. Perhaps most importantly, the primacy of existence provides the capacity for God's judgement without God being directly, or indirectly, affected by the evil being judged. God does not need to possess sin to know sin: God is able to judge the intensity of sin as God perceives existence. One result of Sadra's existentialism is "The unity of the intellect and the intelligible" (Arabic: Ittihad al-Aaqil wa l-Maqul. As Henry Corbin describes: Substantial motion Another central concept of Mulla Sadra's philosophy is the theory of "substantial motion" (Arabic:al-harakat al-jawhariyyah), which is "based on the premise that everything in the order of nature, including celestial spheres, undergoes substantial change and transformation as a result of the self-flow (sarayan al-wujud) and penetration of being (fayd) which gives every concrete individual entity its share of being. In contrast to Aristotle and Avicenna who had accepted change only in four categories, i.e., quantity (kamm), quality (kayf), position (wad’) and place (‘ayn), Sadra defines change as an all-pervasive reality running through the entire cosmos including the category of substance (jawhar)." Existence as reality Mulla Sadra held the view that Reality is Existence. He believed that an essence was by itself a general notion, and therefore and does not, in reality, exist. To paraphrase Fazlur Rahman on Mulla Sadra's Existential Cosmology: Existence is the one and only reality. Existence and reality are therefore identical. Existence is the all-comprehensive reality and there is nothing outside of it. Essences which are negative require some sort of reality and therefore exist. Existence therefore cannot be denied. Therefore, existence cannot be negated. As Existence cannot be negated, it is self-evident that it Existence is God. God should not be searched for in the realm of existence but is the basis of all existence. Reality in Arabic is "Al-Haq", and is stated in the Qur'an as one of the Names of God. To paraphrase Mulla Sadra's Logical Proof for God: There is a being This being is a perfection beyond all perfection God is Perfect and Perfection in existence Existence is a singular and simple reality That singular reality is graded in intensity in a scale of perfection That scale must have a limit point, a point of greatest intensity and of greatest existence Therefore, God exists Causation