Philosopher and giant of Islamic learning. He wrote on the natural world, medicine, religion, philosophy, and theology, and for a time served as Vizier (first minister of the sovereign) in Persia. His very extensive metaphysics included a logical proof of God's existence which he felt complemented but did not displace revelation as our primary way of knowing about God. His writings on Aristotle were translated into Latin and reintroduced Aristotelianism (with some elements of Neo-Platonism) into Christian Europe.