“Custom, in the strict sense of the word,” well says Westermarck, “involves a moral rule....  Society is the school in which men learn to distinguish between right and wrong.  The headmaster is custom."[260] Custom is not only the basis of morality but also of law.  “Custom is law."[261] The field of theoretical morality has been found so fascinating a playground for clever philosophers that there has sometimes been a danger of forgetting that, after all, it is not theoretical morality but practical morality, the question of what men in the mass of a community actually do, which constitutes the real stuff of morals.[262] If we define more precisely what we mean by morals, on the practical side, we may say that it is constituted by those customs which the great majority of the members of a community regard as conducive to the welfare of the community at some particular time and place.  It is for this reason—­i.e., because it is a question of what is and not of merely what some think ought to be—­that practical morals form the proper subject of science.  “If the word ‘ethics’ is to be used as the name for a science,” Westermarck says, “the object of that science can only be to study the moral consciousness as a fact."[263]

Lecky’s History of European Morals is a study in practical rather than in theoretical morals.  Dr. Westermarck’s great work, The Origin and Development of the Moral Ideas, is a more modern example of the objectively scientific discussion of morals, although this is not perhaps clearly brought out by the title.  It is essentially a description of the actual historical facts of what has been, and not of what “ought” to be.  Mr. L.T.  Hobhouse’s Morals in Evolution, published almost at the same time, is similarly a work which, while professedly dealing with ideas, i.e., with rules and regulations, and indeed disclaiming the task of being “the history of conduct,” yet limits itself to those rules which are “in fact, the normal conduct of the average man” (vol. i, p. 26).  In other words, it is essentially a history of practical morality, and not of theoretical morality.  One of the most subtle and suggestive of living thinkers, M. Jules de Gaultier, in several of his books, and notably in La Dependance de la Morale et l’Independance des Moeurs (1907), has analyzed the conception of morals in a somewhat similar sense.  “Phenomena relative to conduct,” as he puts it (op. cit., p. 58), “are given in experience like other phenomena, so that morality, or the totality of the laws which at any given moment of historic evolution are applied to human practice, is dependent on customs.”  I may also refer to the masterly exposition of this aspect of morality in Levy-Bruhl’s La Morale et la Science des Moeurs (there is an English translation).

Practical morality is thus the solid natural fact which forms the biological basis of theoretical morality, whether traditional or ideal.  The excessive fear,