Moral philosophy is probably the most difficult branch of those various disciplines of the human spirit summed up in the general conception of philosophy. This difficulty is one which all the thinkers of our period recognised. Many of them, occupied with other problems on the psychological or metaphysical side, did not write explicitly upon ethics. Yet the problem of ethics, its place, significance and authority, is but the other side of that problem of freedom which has appeared throughout this development as central and vital. The ethical consciousness of man has never been content for long with the assertion that ethics is a purely positive science, although it has obviously a positive side. The essence of morality has been regarded as not merely a description of what exists, but what might, should or ought to exist. Ethics is normative, it erects or endeavours to outline a standard which is an ideal standard. This is the characteristic of ethics, and so long as the moral conscience of humanity, individually and collectively, does not slumber nor die, it will remain so. This conflict between the ideal and the real, the positive and normative is indeed the chief source of pain and conflict to man, but without it he would cease to be human. Whatever the difficulties, the philosopher who aspires to look upon human life as a whole must give _some_ interpretation of this vital aspect of human consciousness. It is in this connection that a solution of the problem of freedom is so valuable, for under a purely determinist and positivist reading of life, the moral sentiments become mere data for an anthropological survey, the hope and tragedy of human life are replaced, comfortably perhaps for some, by an interpretation in which the true significance of ethics is lost.