A classic of theology and philosophy, St. Thomas Aquinas`s Summa Theologica , or Summa Totius Theologiae , is the author`s greatest work and the second of his two expansive summas. Aquinas applies a schematic logic to this summary of all theology, dividing into three sections: The first deals with the nature of God and the universe, the second with morality, and the third with Jesus Christ and the sacraments. Thomas Aquinas died in the midst of writing the third section.