Summa Theologica by Thomas Aquinas.

Thomas Aquinas sums up the teachings of Roman Catholic theology for our time.

Aquinas believed that the knowledge which comes from reason and experience will agree with what is known through faith and revelation, because both reason and faith come from God. His summary of Christian theology is grounded upon the revelations of the Bible, but his systematic explanations also draw on the logic and philosophy of the ancients, especially Aristotle.

About the author:
Thomas Aquinas was an Italian member of the Dominican order who taught theology for many years here at the University of Paris. His work is praised by scholastics at universities across Europe.