The Summa Theologiæ of Saint Thomas Aquinas is a work that has held a place of prominence in the disciplines of theology and philosophy since the time of Thomas himself. It was written when Latin was the language of scholarship, a common tongue that crossed Europe's volatile political boundaries and facilitated the growth of universities, many of which are still standing today. It is the hope of those responsible for this edition, that having the original Latin text and a respected English translation side by side will not only give those who are not ready to tackle the of Saint Thomas unaided access to his own words, but will inspire them and assist them in their pursuit of this language. They will likely discover, as many have before them, that Thomas is more easily understood in the tongue in which he wrote than he is in any other. This Third Volume contains the Treastise on the Last End; the Treatise on Human Acts: Acts Peculiar to Man; the Treatise on the Passions; the Treatise on the Habits; and the Treatise on the Habits in Particular, the Good Habits, i.e., the Virtues.