Aquinas (1225-1274) lived just after Averroes, about 200 years after Avicenna. Augustine was the bringer of Plato into Christian Europe, and Aquinas was the bringer of Aristotle into medieval Europe thanks to his reading of Islamic authors. He studied at the University of Naples until he was 16. Because he was brilliant, the Dominican order offered to support his scholarship. He became a Dominican, then was kidnapped by his parents who wanted him to come back home. According to the legend his brother’s brought him a prostitute, but he drove her away. Then the Pope intervened, and he went back to being a Dominican.
Aquinas was primarily influenced by Ghazali and Averroes, both of whom were critics of Avicenna. Three years after his death, Aquinas was excommunicated for heresy due to following Averroes’ interpretation of Aristotle’s works, but later the Church reversed its position. This is after Aquinas defended the Church again and again as the only source of true authority and knowledge. 50 years after his death, he was pronounced a Saint. Later, at the First Vatican Council (1868) he was pronounced the central thinker of the Catholic Church.
As an Averroist Aristotelian, Aquinas believed that universals are real beings that are even more real than physical objects. His argument for the existence of God shows this. He argues that all things are dependent on, possible because of, and less than a highest thing, which must be God, Being itself. Thus, like later European thought, Being is essence of essences which we will see in Hegel later. Descartes follows Aquinas’ argument for a highest, most necessary being.