Dr. Lane G. Tipton offers a sustained exposition of the Trinitarian structure of Thomas Aquinas’s theology. The central thesis guiding this entire course is that for Thomas Aquinas, all of theology is essentially theology proper, structured around and governed by his Trinitarian doctrine of exitus (departure) and reditus (return). Specifically, Thomas conceives the eternal processions of the Son and Spirit from the Father in the Trinity (exitus) as the exemplary cause and reason for the temporal procession of rational creatures in creation (exitus). Likewise, the return (reditus) of the Son and Spirit to the Father in the Trinity is the exemplary cause for the return of rational creatures to God through deifying, elevating grace (reditus). Thus, Trinitarian theology focused on the eternal processions and missions of the divine persons shapes and frames Thomas’s entire theological system. It serves as the conceptual architecture linking God’s works ad intra in himself and his works ad extra in relation to creatures. Every doctrinal locus in Thomas—from the Trinity to creation to eschatology—is ultimately structured around the eternal processions and temporal missions of the Son and Spirit that enable the creature’s gracious return to participation in the divine life.