The Summa Theologica (or the Summa Theologiae or simply the Summa, written between 1265–1274) is the most famous work of Thomas Aquinas, even though 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 by Leni)
This is part seven, the first part of the Pars Prima Secundae, consisting of the Treatises on the Last End and on Human Acts.