Avicenna

Avicenna (Ibn Sina) was the greatest philosopher of the Islamic world and one of the most influential minds of the Middle Ages, master of medicine as well as metaphysics (his Canon of Medicine ruled the field for centuries). In his vast Book of Healing he reshaped the Aristotelian inheritance through a Neoplatonic lens — partly under the spell of the so-called Theology of Aristotle, in truth a paraphrase of Plotinus's Enneads.

He distinguished necessary from possible being, and made God the one Necessary Existent from whom all else flows by emanation through a series of Intellects; he argued, with his 'floating man', that the soul knows itself directly, apart from the body. Through Latin translation his metaphysics shaped Aquinas and the whole of scholasticism.