Summa Theologiae

Thomas Aquinas's systematic synthesis of Christian theology and Aristotelian philosophy, organized into questions and articles across three main parts covering God and creation, human action and the virtues, and Christ and the sacraments. Aquinas intended it as an ordered introduction for beginning theology students. He left it unfinished at his death in 1274, stopping partway through the third part; his followers later compiled a supplement from his earlier writings to complete the work.