Sohravardi’s illuminative theosophy includes innovative principles that one cannot find in the Peripatetic theosophy. It has become the basis for the subsequent generations of thinkers and has emerged as a turning point in the history of philosophy.The doctrine of Izafeye Ishraqiyyeh (illumiationist relation), which has been introduced as an explanation for the relation between cause and its effect, is one of the foundational principles of this philosophy. Since the causal relation necessarily leads to the relation between the creator and creature, Moslem philosophers before Sohravardi tried to prove a deep relation between the two. As an example, Avicenna, by holding that the contingent is a composite of existence and quiddity and that the essential possibility of quiddity is the criterion of the dependency of entity to its cause considered the contingent as dependent on its cause for its existence. By rejecting some of the Peripatetic principles on the basis of Izafeye Ishraqiyyeh, Sohravari held that the effect has an illuminational relation with its cause and in this way he replaced contingency with luminous need. With such an interpretation, a deeper relation between the cause and its effect was established. Davani and Mirdamad are among the followers of this theory who, despite giving a new interpretation of his theory to evade its defects, preferred Sohravardi’s views to Avicenna’s.