This new Companion to Aquinas features entirely new chapters written by internationally recognized experts in the field. It shows the power of Aquinas's philosophical thought and transmits the worldview which he inherited, developed, altered, and argued for, while at the same time revealing to contemporary philosophers the strong connections which there are between Aquinas's interests and views and their own. Its five sections cover the life and works of Aquinas; his metaphysics, including his understanding of the ultimate foundations of reality; his metaethics and ethics, including his virtue ethics; his account of human nature; his theory of the afterlife; his epistemology and his theory of the intellectual virtues; his view of the nature of free will and the relation of grace to free will; and finally some key components of his philosophical theology, including the incarnation and atonement, Christology, and the nature of original sin.