Cutting through contemporary confusions with his characteristic rigor and aplomb, Steven A. Long offers the most penetrating study available of St. Thomas Aquinas's doctrine of the intention, choice, object, end, and species of the moral act. Many studies of human action and morality after Descartes and Kant have suffered from a tendency to split body and soul, so that the intention of the human spirit comes to justify whatever the body is made to do. The portrait of human action and morality that arises from such accounts is one of the soul as the pilot and the body as raw material in need of humanization. In this masterful study, Steven Long reconnects the teleology of the soul with the teleology of the body, so that human goal-oriented action rediscovers its lost moral unity, given it by the Creator who has created the human person as a body-soul unity.