devoted his rest of life to teach the intellectual sciences, particularly his own teachings Transcendent Theosophy. During his time in Shīrāz, Ṣadrā began writing treatises that synthesized wide-ranging strands of existing Islamic systems of thought at Khan School. The ideas of his school, which may be seen as a continuation of the School of Iṣfahān of Mīr Dāmād and Shaykh Bahāʾī, were promulgated after Sadrā's death by his pupils, several of whom would become sought-after thinkers in their own right, such as, Mullā Muḥsin Fayḍ Kāshānī (Mulla Sadra's son-in-law), and ʿAbd Razzāḳ Lāhidjī. Although Ṣadrā's influence remained limited in the generations after his death, it increased markedly during the 19th century, when his ideas helped inspire a renewed Akhbārī tendency within Twelver Shīʿism. In recent times, his works have been studied in Iran, Europe, and America.He died in Basra after the Hajj and was buried in the present-day city of Najaf, Iraq. Philosophical ideas Existentialism Although Existentialism as defined nowadays is not identical to Mulla Sadra's definition, he was the first to introduce the concept. According to Mulla Sadra, "existence precedes the essence and is thus principal since something has to exist first and then have an essence." It is notable that for Mulla Sadra this was an issue that applied specifically to God and God's position in the universe, especially in the context of reconciling God's position in the Qur'an with the Greek-influenced cosmological philosophies of Islam's Golden Era. Mulla Sadra's metaphysics gives priority to existence over essence (i.e., quiddity). That is to say, essences are variable and are determined according to existential "intensity" (to use Henry Corbin's definition). Thus, essences are not immutable. The advantage to this schema is that it is acceptable to the fundamental statements of the Qur'an, even as it does not necessarily undermine any previous Islamic philosopher's Aristotelian or Platonic foundations. Indeed, Mulla Sadra provides immutability only to God, while intrinsically linking essence and existence to each other, and to God's power over existence. In so doing, he provided for God's authority over all things while also solving the problem of God's knowledge of particulars, including those that are evil, without being inherently responsible for them — even as God's authority over the existence of things that provide the framework for evil to exist. This clever solution provides for freedom of will, God's supremacy, the infiniteness of God's knowledge, the existence of evil, and