Thus does St. Thomas announce the theme of Book Four of SCG, in which he discourses on the. mysteries that can make men joyful and glad forever-the mysteries of salvation. Faith is the initial knowledge by which we enter into these mysteries, and in this volume St. Thomas makes the transition from "divine things according as the natural reason can arrive at the knowledge [of them]" to "those divine things that have been divinely revealed to us to be believed, since they transcend the human intellect."
Accordingly, this important volume considers the inner life of the divine Trinity. Thence it studies Jesus Christ, Who is Incarnate God, under several aspects: as the man who suffered and died; as the God Who raised the dead, commanded the elements, forgave sin, rose from the dead and ascended into heaven. St, Thomas then treats of Christ's dual nature in one divine person, and how He extends His power' grace, presence and teaching through the Sacraments. Finally, Aquinas examines man's immortality salvation and damnation; the Last Judgment and what will follow it.