Aquinas, Summa Theologica, 1265 - 1274.
The Summa Theologica is Thomas Aquinas’s magnum opus and one of the most influential works in Western philosophy and Christian theology. Written as a comprehensive guide for theology students, it systematically presents Aquinas’s understanding of God, creation, humanity, and the path to salvation. The work is structured into three main parts and was left unfinished at the time of Aquinas’s death.