The school of Illuminationism, which is significant for our understanding of Mulla Sadra's philosophy, was founded by Shahab al-Din Yahya b. Habash b. Amirak Suhrawardi, known also as Shaykh al-Ishraq, the master of illumination. This chapter explains how Suhrawardi, in his introduction to Hikmat al-Ishraq, refers explicitly to Plato and the place of his ideas in the development of the illuminative philosophy. In Suhrawardi's view, the history of philosophy did not begin with Thales in 600 BC. Instead Hermes is considered by this Muslim thinker to be the father of illuminative philosophical thinking or wisdom. Hermes was followed by sages from Greece, Persia and the Muslim world. To demonstrate similarities between Mulla Sadra's opposition to Illuminationism, in particular the doctrine of the primacy of essence, and Heidegger's negative attitude towards nihilism, we need to highlight the relationship between Plato's metaphysics and Illuminationism.