It is no wonder, therefore, that the evolutionists of our day should claim to have given a wholly new character to ethical enquiries. In Hume’s time a philosopher who denied the innateness of moral sentiments, and held that they must have a natural history, had only the limits of the individual life within which to trace this history. These limits did not give room enough for even a plausible derivation of moral interests from animal wants. It is otherwise when the history may be supposed to range over an indefinite number of generations. The doctrine of hereditary transmission, it is held, explains to us how susceptibilities of pleasure and pain, of desire and aversion, of hope and fear, may be handed down with gradually accumulated modifications which in time attain the full measure of the difference between the moral man and the greater ape. Through long ages of interaction between the human organism and the social medium in which it lives, there has been developed that sensibility of principle which feels a stain like a wound; that faculty of moral intuition which not only pronounces unerringly on the social tendencies of the commonest forms of human action, but enables us in some measure to see ourselves as others see us; that civil spirit through which the promptings of personal passion are controlled even in the individual by the larger vision and calmer interest of society. (§5 ¶1)

Thus it would seem that for the barren speculation of the old metaphysical ethics we should seek a substitute in a scientific Culturgeschichte; in a natural history of man conducted on the same method as an enquiry into any other form of life which cannot be reduced to the operation of strictly mechanical laws. For the later stages of this history we have, of course, abundant materials in the actual monuments of human culture—linguistic, literary, and legal—and these, the physiologist may say, have yet to be considered in connexion with the data which his own science furnishes. It is true that, however far they carry us back, however great the variations of moral sentiment to which they testify, they do not bring us to a state of things in which the essential conditions of that sentiment were absent. The most primitive man they may exhibit to us is already conscious of his own good as conditioned by that of others, alrseady capable of recognising an obligation. But the theory of descent and evolution opens up a vista of possibilities beyond the facts, so far ascertained, of human history, and suggests an enquiry into the antecedents of the moralised man based on other data than the records which he has left of himself. Such enquiry, it is thought, will in time give us the means of reducing the moral susceptibilities of man to the rank of ordinary physical facts, parts of one system, and intelligible by the same methods, with all the natural phenomena which we are learning to know. Man will then have his ascertained place in nature, as perhaps the noblest of the animals, but an animal still. (§5 ¶2)