St. Thomas Aquinas

The Summa Theologica is the best-known work of Thomas Aquinas, and although unfinished, "one of the classics of the history of philosophy and one of the most influential works of Western literature." The work is intended as a manual for beginners in theology and also a compendium of all of the main theological teachings of the Church. It presents the reasoning for almost all points of Christian theology in the West. This is part 1-2, 'Pars Prima Secundae'.

Books like Summa Theologica Part I-II ("Pars Prima Secundae")

Your next favorite book is out there