A systematic manual presents Catholic moral theology as the study of human conduct ordered to God as the last end, integrating reason with revealed truth and employing Thomistic principles. It lays foundational definitions and rules, distinguishes moral theology from ethics, faith, synderesis, and conscience, and treats law, virtues, vices, culpability, and the means of tending to the supernatural end. Practical and pastoral concerns receive attention through casuistical examples and discussions of sacramental and pastoral obligations, enabling application to modern moral problems while emphasizing formation of conscience and the positive cultivation of virtue.