Summa Theologica Part III (Tertia Pars) Thomas Aquinas - The Summa Theologiae (Latin: Compendium of Theology or Theological Compendium; also subsequently called the Summa Theologica or simply the Summa, written 1265-1274) is the best-known work of Thomas Aquinas (c.1225-1274), and although unfinished, 'one of the classics of the history of philosophy and one of the most influential works of Western literature.' It is intended as a manual for beginners in theology and a compendium of all of the ...