Metaphysics has always been one of the pivotal topics of debate between Muslim philosophers; this may especially be said about Ibn Taymiyyah and Ibn Sīnā. For Ibn Taymiyyah, the subject matter of metaphysics is absolute and universal Existence (al-wujūd al-kullī al-muṭlaq), namely God, which is known by investigating the intrinsic attributes of His essence (lawāhiq al-dhātiyyah). For Ibn Sīnā, it is al-mawjūdāt (existing beings), the whole of caused being (kullu mawjūd ma‘lūl), or the principle abstracted from the whole of caused being, and not God. Such clear and discrete views resulted in different notions of God’s existence as well as of the origination of the universe.