Aquinas' "Summa Theologica" is his most famous work. It was intended as a manual for beginners as a compilation of all of the main theological teachings of that time and consists of a summary of the reasonings for almost all points of the Catholic faith. It is the fullest presentation of his views and covers the widest range of subjects - reason, sin, just war to name but a few - in detailed philosophical language. He worked on it from 1265 until...