An investigation of this kind cannot be confined to feelings and ideas prevalent in any particular society or at any particular stage of civilisation. Its subject-matter is the moral consciousness of mankind at large. It consequently involves the survey of an unusually rich and varied field of research--psychological, ethnographical, historical, juridical, theological. In the present state of our knowledge, when monographs on most of the subjects involved are wanting, I presume that such an undertaking is, strictly speaking, too big for any man; at any rate it is so for the writer of this book. Nothing like completeness can be aimed at. Hypotheses of varying degrees of probability must only too often be resorted to. Even the certainty of the statements on which conclusions are based is not always beyond a doubt. But though fully conscious of the many defects of his attempt, the author nevertheless ventures to think himself justified in placing it before the public. It seems to him that one of the most important objects of human speculation cannot be left in its present state of obscurity; that at least a glimpse of light must be thrown upon it by researches which have extended over some fifteen years; and that the main principles underlying the various customs of mankind may be arrived at even without subjecting these customs to such a full and minute treatment as would be required of an anthropological monograph. Possibly this essay, in spite of its theoretical character, may even be of some practical use. Though rooted in the emotional side of our nature, our moral {3} opinions are in a large measure amenable to reason. Now in every society the traditional notions as to what is good or bad, obligatory or indifferent, are commonly accepted by the majority of people without further reflection. By tracing them to their source it will be found that not a few of these notions have their origin in sentimental likings and antipathies, to which a scrutinising and enlightened judge can attach little importance; whilst, on the other hand, he must account blamable many an act and omission which public opinion, out of thoughtlessness, treats with indifference. It will, moreover, appear that a moral estimate often survives the cause from which it sprang. And no unprejudiced person can help changing his views if he be persuaded that they have no foundation in existing facts. CHAPTER I THE EMOTIONAL ORIGIN OF MORAL JUDGMENTS