This text is a bilingual Arabic-English translation of one of the most important metaphysical works of the Persian Muslim philosopher known as Mulla Sadra & Sadr al-Din Muhammad al-Shirazi (1574-1641). In this work Mulla Sadra develops an anti-Platonic philosophical position which is non-Aristotelian. He holds that "existents" are ontologically prior to "essence" & that there are two different realms -- the mind dependent domain & entities which exist independent of the mind. Mulla Sadra's views became very popular among Iranian Muslim philosophers & eventually were instrumental in destroying the Aristotelian school of thought in the Islamic world. The translator, Dr. Parviz Morewedge, is the Secretary-Treasurer of the Society for the Study of Islamic Philosophy & Science & has published ten books & numerous articles in Islamic Philosophy & Mysticism.