In the lectures below, Dr. K. Scott Oliphint examines the theological prolegomena of Thomas Aquinas, one of the foremost scholastic theologians of the medieval church. The six-part series includes an analysis and critique of Aquinas’s foundation of knowledge (principium cognoscendi) and foundation of being (principium essendi). Oliphint contrasts Thomism’s tendency to overestimate the ability of natural reason with the Protestant Reformers’ insistence that human reason, like the will and affections, has been impaired by the fall. Moreover, he notes Aquinas’s attempt to construct Christian theology on the basis of a modified version of Aristotle’s “substance metaphysic” rather than on the foundation of the Triune God’s self-revelation in Scripture. These lectures serve as part of the curriculum for Reformed Baptist Seminary’s course HT 512 Medieval Church.