The history of the science does not come within the purpose of this work. The greatness of the speculative and practical questions involved in the subject, clearly and impressively apparent when once brought forward, could not fail to awaken and hold the most earnest interest of the human mind. They concerned the powers and possibilities of man in the crowning endowments of his nature, and in the highest ascent of their evident intention and adaptation. They touched the great problems of personal and social welfare in the most vital relations and decisive interests. So the old sages became moralists and their great themes were the themes of virtue and duty. Not very deeply, however, did they, for centuries, succeed in penetrating the rational principles of the moral life and the authority of the moral judgments. Yet clear gems of thought and deep suggestion mark the pathway of their thinking. In passing on, and over from pagan into Christian development, the treatment was mostly in connection with religious truths, and as involved in theological doctrine. In the light of the Christian Scriptures the whole subject came under a new illumination. The various duties, however, in the different relations of life, were permitted to rest, without much theorizing, on the warrant of supernatural revelation and divine precept. Down through the early Christian period, and the centuries of mediæval scholasticism, and on through the Renaissance and the Reformation and the subsequent dogmatic period of Protestant theology, ethics continued to be treated simply as a division of theology, based almost wholly on the Sacred Scriptures, with but little inclusion of any effort to determine its natural basis and significance. But with the age of modern philosophy and science a new interest and direction came to ethical inquiry. Explanation began to be sought for the unique authority of the ethical judgments, and concerning the place of the moral power in the essential constitution of the human soul. Special emphasis was given to the fact that, even apart from the precepts of revelation, man is bound to rectitude by an imperative within him, which is not of his choice, but claims the right to dominate his choices. And since the seventeenth century the ethical constitution of humanity, together with the nature and grounds of right, has been made, apart from theology, the distinct and separate theme of scientific and philosophical investigation and discussion. It has been among the leading subjects of rational inquiry and constructive effort. Especially in Great Britain and in our own country has the inquiry been conducted on this basis, and directed to the exhibition of the natural foundation and character of the ethical distinctions and judgments, and to a systemization of the ethical realities and laws thus determinable. The work thus done has created an immense literature, and established a body of securely authenticated scientific results.