Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Islamic metaphysics refers to the study of metaphysics within Islamic philosophy. Avicenna''s proof for the existence of God was the first ontological argument, which he proposed in the Metaphysics section of The Book of Healing. This was the first attempt at using the method of a priori proof, which utilizes intuition and reason alone. Avicenna''s proof of God''s existence is unique in that it can be classified as both a cosmological argument and an ontological argument. "It is ontological insofar as necessary existence in intellect is the first basis for arguing for a Necessary Existent". The proof is also "cosmological insofar as most of it is taken up with arguing that contingent existents cannot stand alone and must end up in a Necessary Existent."