Summary: The author of the Principles Preface to the Third Edition reflects on the ancient and modern course of ethical thought, focusing on the contributions of the Greeks, particularly Aristotle, to moral science. A distinction is made between Hedonism and Eudemonism, emphasizing the importance of individual and personal development. The text critiques rationalism, highlighting the flaws of extreme rationalism and advocating for a balanced ethical approach based on reason and personal fulfillment. The idea of self-realization, the dualism between reason and sensibility, and the dynamic nature of character development are explored. The discussion touches on philosophical concepts such as ethics of reason, ethics of personality, moral ideal, and the role of self-control in moral progress. The narrative delves into the influence of philosophy on ethical theory, contrasting various philosophical schools and their interpretations of morality, ultimately highlighting the importance of individual autonomy and ethical reflection in shaping a virtuous life.