What was a central idea in Thomas Aquinas's Summa Theological?

The Summa Theologica, as its title indicates, is a "theological summary." It seeks to describe the relationship between God and man and to explain how man’s reconciliation with the Divine is made possible at all through Christ. To this end, Aquinas cites proofs for the existence of God and outlines the activities and nature of God. Aquinas attempts to explain the origin, operation, and purpose of the entire universe.