Catholic Moral theology, known as Christian Ethics in non-Catholic contexts, encompasses Roman Catholic social teaching, medical ethics, sexual ethics, and moral virtue and theory.
Moral theology seeks to define and address things such as the different methods of moral discernment, the definitions of right and wrong, good and evil, sin and virtue, etc.
Studies in moral theology are numerous and wide-ranging. The literature for research is very large and diverse.
Thomas Aquinas (1225-1274), Summa Theologica, Prima Secundae Partis. Section on law. English translation. The Summa Theologica of St. Thomas Aquinas, 2nd. and rev. ed., trans. by the Fathers of the English Dominican Province, 1920.