The conventional interpretation of Thomas Aquinas's concept of "moral science" casts it as a knowledge of moral rules that are the outcome of a deductive method of theoretical reason. However, there is a practical moral science that is possessed by ordinary people who are capable of a moral wisdom that is not derived from philosophy. The doctrine concerning this moral science is found in the texts of Aquinas as he takes up and strengthens the philosophy of Aristotle. This book examines how moral science, then, is not a theoretical set of conclusions imposed on the will, but it is rather the grasping of a whole set of human ends that are intellectually apprehended by a compositive method. (Series: Philosophy: Science and Research / Philosophie: Forschung und Wissenschaft - Vol. 42)