12. Moral Theology is served not only by the various branches of philosophy (such as Ethics, Theodicy, Psychology, Logic), but also by many of the natural sciences. Thus: (a) Medicine and Physiology are useful for understanding the morality and imputability of acts; (b) Sociology and Economics may throw light on problems concerning justice; (c) Jurisprudence is, of course, closely related to questions concerning duties that arise from human laws; (d) History confirms the teachings of Christian morality by the lessons of experience. 13. The Method to Be Followed in Moral Theology.-(a) The positive method is a simple statement of moral principles and doctrines, with little attention to argument, except such as is found in the positive sources (e.g., scripture, tradition, the decisions of the Church). (b) The Scholastic method is a scientific statement of moral teaching through accurate definition of terms, systematic coordination of parts, strict argumentation and defense, attention to controversies, and recourse to philosophy and other natural knowledge. (c) The casuistic method, or case-system, is the application of moral principles to the solution of concrete problems of lawfulness or unlawfulness. 14. The Scholastic method is the one best suited for the study of Moral Theology, because it is more scientific, and fits one better to understand, retain, and apply what one learns. But it is not exclusive of the other methods, since it perfects the positive method, and is the groundwork for the case method. Each method has a special suitability for certain ends. Thus: (a) the positive method is well adapted to preaching, and hence was much in favor with the Fathers of the Church, as can be seen from their moral homilies and treatises; (b) the Scholastic method is the best for study, teaching, apologetic, and was followed by the great classical works of theology in the Middle Ages and later; (c) the case method is very helpful to the seminarian and the priest in the exercise of the ministry of the confessional. 15. The History of Moral Theology.--There are three periods in the history of Moral Theology: the Patristic, the Medieval, and the Modern. (a) The Patristic Period (1st to 12th century).--The moral writings of the-Fathers are popular, exhortatory, and occasional; and it is not till the Middle Ages that we meet with works of systematic Moral Theology. The following are among the most notable moral works of the Fathers: the _Paedagoga_ of Clement of Alexandria (d. about 217), which explains what the everyday life of the Christian should be; the _Catecheses_ of St. Cyril of Jerusalem (d. 386); the _De Officiis Ministrorum_ of St. Ambrose (d. 397), a Christian counterpart of Cicero’s work _De Officiis_; the _De Civitate Dei_ of St. Augustine (d. 430), which contrasts love of God and love of self; the _Expositio in Job seu Moralium libri XXV_ of St. Gregory the Great (d. 604), which consists of moral instructions based on the Book of Job.