Summa Theologica - 13 Tertia Pars, The Saviour: His Incarnation and His Salvific Acts - Saint Thomas Aquinas

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 1-59 of the Tertia Pars ("Third Part"), comprising a Treatise on the Saviour: the Mystery of the Incarnation in itself (questions 1-26), and on what things the Incarnate Son of God did or suffered in the human nature united to Him (questions 27-59).