Summa of Philosophy According to the Mind of the Angelic Doctor St. Thomas Aquinas - Ethics, Part III, Volume III - Salvatore Maria Roselli

This third volume completes Roselli’s Summa of Philosophy, presenting a systematic account of ethics within the Thomistic tradition of Thomas Aquinas. It brings together the principles of logic and metaphysics developed in the earlier volumes and applies them to the study of human action and moral order.

The work begins with human acts, analyzing their voluntariness, moral specification, and the role of reason and will in determining moral responsibility. Roselli explains how moral evaluation depends on conformity to rational nature and ultimately to the order of being.

It then treats the virtues and vices, focusing on how stable habits perfect human powers and direct them toward the good. Special attention is given to the cardinal virtues—prudence, justice, fortitude, and temperance—as the structural foundation of moral life.

A central section is devoted to natural law, understood as the rational participation of human beings in the eternal law. Roselli presents it as the objective foundation of moral obligation, accessible to reason and binding in conscience.

The volume concludes with considerations on happiness and the ultimate end of human life, presenting beatitude as the perfection of rational nature in the attainment of its highest good. Throughout, Roselli maintains a clear scholastic method, presenting ethics as a rational science grounded in human nature and ordered toward its ultimate fulfillment.