The Summa is composed of three major parts, each of which deals with a major subsection of Christian theology.

The Summa Theologica is meant to summarize the history of the cosmos and provide an outline for the meaning of life itself.

The Summa theologiae is written in a form common to treatises of that age. All of theology is divided into its major topics. These, in turn, are divided into subtopics described by Thomas as 'questions. " The first "question" in the Summa theologiae deals with The nature of Theology itself, the second with God's existence.

The Summa Theologiae is the best-known work of Thomas Aquinas (c. 1225–1274). Although unfinished, the Summa is "one of the classics of the history of philosophy and one of the most influential works of Western literature." It was intended as an instructional guide for theology students, including seminarians and the literate laity. It was a compendium of all of the main theological teachings of the Catholic Church. It presents the reasoning for almost all points of Christian theology in the West. The Summa's topics follow a cycle: the existence of God; Creation, Man; Man's purpose; Christ; the Sacraments; and back to God.

Thomas Aquinas, was an Italian Dominican friar and Catholic priest who was an immensely influential philosopher, theologian and jurist in the tradition of scholasticism, within which he is also known as the "Doctor Angelicus" and "Doctor Communis".He is heralded as the most influential Western medieval legal scholar and theologist. The name "Aquinas" identifies his ancestral origins in the county of Aquino (in the present-day Lazio region), an area where his family held land until 1137.