This book explores the issue of knowledge by presence as an epistemological problem in philosophy. Al-Ilm al-Huduri (knowledge by presence) deserves as an epistemological bridge between philosophy and mysticism. This book is a comparative study of the epistemology of Suhrawardi and Mulla Sadra Shirazi, two Muslim thinkers of the 6th/12th and 11th/17th century. It focuses on two main issues: Illuminative theory of knowledge and, in the framework of this theory, Mulla Sadra's doctrine of knowledge by presence (al-'ilm al-huduri) studied in the context of his philosophical system (al-hikmah al-muta'aliyah). Mulla Sadra's multidimensional methodology is also discussed in this book. The aim of this study is to explore the Mulla Sadra's theory of knowledge by presence, al-'ilm al-huduri, and examine it as an epistemological bridge between philosophy and mysticism within the context of Mulla Sadra's philosophical system (al-hikmah al-muta'aliyah). Hence, Mulla Sadra's doctrine of knowledge by presence is the corner stone of his epistemological system. In the light of this doctrine, he gives a new definition of knowledge, an innovative interpretation of its division into al-'ilm al-huduri and al-'ilm al-husuli, and, finally, a systematic chain of various kinds of knowledge by presence (e.g., self-knowledge, God's knowledge of His Essence and God's knowledge of things). These three aspects of his doctrine have been surveyed and, in comparing them with Suhrawardi's theory, evaluated in this book."