Second, there is a contradiction between the idea of God on which Judaism is founded, and the philosophical, Aristotelian idea of God. The philosophical idea is that God is intellect, whereas the religious idea is that it cannot be known what God is. Maimonides (1135–1204) sums up this problem with what he calls “very disgraceful conclusions” in the following passage.

Namely it would follow that the Deity, whom everyone who is intelligent recognizes to be perfect in every kind of perfection, could as far as all beings are concerned, produce nothing new in any of them; if he wished to lengthen a fly’s wing or shorten a worm’s foot, he would not be able to do so. But Aristotle would say that he would not wish it and that it is impossible to will something different from what is; that it would not add to his perfection, but would perhaps from a certain point of view be a deficiency.

Third, Maimonides rejected the Aristotelian doctrine of the eternity of the world. Although he could offer no conclusive rational justification for this rejection, neither did he affirm that this was an issue in which religion was definitively correct.

St. Thomas Aquinas (1224–1274) was born in Rocaseca, Italy. He began his religious studies in a Benedictine monastery and studied liberal arts at the University of Naples. He entered the Dominican Order of Preachers when he was only 20. He studied theology in Paris, attaining his doctorate in 1256, and taught there until 1259. Aquinas then lectured on theology and philosophy at Dominican monasteries near Rome, and then returned to the University of Paris. He taught for a year in Naples in 1272. Aquinas died near his place of birth, while traveling to a church council in Lyons.

During his teaching career, which spanned from 1252 to 1273, Aquinas wrote extensively. He lucidly solved long-standing problems in the interpretation of Aristotle, made clear distinctions between Christian theology and philosophy, and demonstrated how the two were compatible on many subtle points.