The Summa Theologica (or the Summa Theologiae or simply the Summa, written 1265–1274) is the most famous work of Thomas Aquinas (c. 1225–1274) although it was never finished. It was intended as a manual for beginners and a compilation of all of the main theological teachings of that time. It summarizes the reasoning for almost all points of Christian theology in the West, which, before the Protestant Reformation, subsisted solely in the Roman Catholic Church. The Summa's topics follow a cycle: the existence of God, God's creation, Man, Man's purpose, Christ, the Sacraments, and back to God. (Summary adapted from the Wikipedia)
This selection of the Summa Theologica covers questions 90-114 of the Prima Secundae («First-half of the Second Part»), comprising Treatises on Law (questions 90-108) and Grace (questions 109-114).