The Cambridge History of English and American Literature in 18 Volumes (1907–21). Volume XIV. The Victorian Age, Part Two. I. Philosophers. § 24. Leslie Stephen. It was natural that men of science with a philosophical turn of mind should be among the first to work out the more general consequences of the theory of evolution. But the wide range which the theory might cover was fairly obvious, and was seen by others who approached philosophy from the point of view of studies other than the natural sciences. Foremost among these was Leslie Stephen, a man of letters keenly interested in the moral sciences. The portion of his writings which bear upon philosophy is small only in relation to his total literary output. His History of English Thought in the Eighteenth Century (1876) places the philosophers and moralists in their due position in the whole literary activity of the period, and is penetrating and usually just in its estimate of their work. A further stage of the same history—The English Utilitarians (1900)—was completed towards the end of his life. His own independent contribution is given in The Science of Ethics (1882). After Spencer’s Data, this is the first book which worked out an ethical view determined by the theory of evolution. As such it is significant. The author had sat at the feet of John Stuart Mill; he had eagerly welcomed Darwin as an ally of the empirical and utilitarian creed; but he came to see that more extensive changes were necessary. Spencer’s compromise between hedonism and evolutionism failed to satisfy him, and he found the ethical bearing of evolution better expressed by the conception of social vitality than by that of pleasure. The great merit of the work consists in its presentation of the social content of morality in the individual mind as well as in the community; but it does not sufficiently recognise the distinction between the historical process traced by the evolution theory and the ethical validity which evolution is assumed to possess.   55