 Rizvi (1999, 224) showed how later philosophers ascribed the ontological primacy of essence (or quiddity) thesis to Suhrawardi who “clearly states that quiddity/essence in itself is a conceptual and unreal a notion as existence”, Suhrawardi noting that “the quiddity of luminosity [i.e., the same as light] is a mental universal” (PI, §141). But it is also true that Suhrawardi’s “phenomenological epistemology of eidetic vision” could easily imply a primacy of essence (Rizvi 1999, 224). The position is eminently nominalist, now that both existence and essence are considered mere mental concepts, reality having been redefined with the new primacy of light. Likewise, his theory of knowledge by presence remains “deeply nominalist and empiricist” (viz. mystical experience) (Walbridge 2000, 169). However, light and essence cannot be synonymous. Both light and darkness exist: “light is the being of things as their instantiating principle in concreto and not their essences” (ibid.). Likewise, light is not identical with substance, since both dark substances and accidental lights exist (Walbridge 2000, 24). Rizvi (1999, 224) notes that entities grasped as essences through presential knowledge are “apparent aspects of what one might regard as ‘light monads’”, an idea whose source appears to be highly Platonic or Neoplatonic (Proclus). 