This work sets out a classical theory of law and political life in which law is an ordinance of reason directed to the common good and promulgated by legitimate authority, unfolding in a hierarchy — eternal law (the divine order), natural law (human participation in that order through practical reason), human law (positive statutes derived from natural law), and divine law (revelation oriented to salvation). It explores how conscience, virtue, and practical reason ground moral obligation, distinguishes just from unjust laws and legitimate from tyrannical rule, and treats justice, punishment, and the proper ends of political community while showing the complementary roles of reason and grace in moral and civic formation.