This article deals with Ibn Sīnā’s criticisms of Aristotle regarding what the place of God should be in the science of metaphysics. From Aristotle’s point of view, the existence of God is proved by the proof of motion in physics and is held as a subject matter in a science that comes after physics, which is metaphysics. According to him, metaphysics is the most sublime science because God is its subject matter. The most striking criticism against Aristotle’s conception of metaphysics was put forward by Ibn Sīnā. From Ibn Sīnā’s point of view, the most important problem encountered in Aristotle’s understanding of metaphysics is that ontology and theology are intertwined. According to him, God cannot be a subject matter in metaphysics, rather, proving the existence of God is the aim of metaphysics. The subject matter of metaphysics is being qua being, and its aim is to prove the Necessary Existent that is the principle of existence. Accordingly, for Ibn Sīnā, metaphysics is an ontological science in terms of its subject and a theological science in terms of its aim. This new conception of metaphysics, developed by Ibn Sīnā, had a profound effect not only on Islamic thought but also on Western philosophy. In a way, the ontotheological notes of Islamic and Western thought from the Middle Ages to the present have progressed through the metaphysical symphony composed by Ibn Sīnā.