This eight-week seminar will investigate some key elements of the Trinitarian theology of St. Thomas Aquinas. First, we will consider the role of speculative theology so as to be cognizant of both the power and the limitations of our speech about the God whose essence is beyond our mental grasp. Second, we will examine the analogy of the word and love, which Thomas held to be the unrivalled image for gaining insight into the ineffable mystery of the Trinity. Third, we will probe Aquinas’s understanding of the divine person as a subsistent relation, a doctrine that gives his theology a superior coherence and clarity for ruling out error and elucidating the faith. And fourth, we will take up the somewhat controversial question of the Filioque, in order to become conversant with this important dogma and vexing historical issue concerning the Holy Spirit’s procession.