  Wright's study of Mill's utilitarianism undoubtedly influenced his understanding of Darwin. Although he rejected Spencer's application of the principle of evolution to history and civilization, he thought many aspects of human behavior and psychology could be treated by the principle of natural selection. Utilitarian ethics provided a model for him. He used the way humans make moral choices as an analogy for unconscious selection in the change of human language over time. Utility is not the motive of moral decision-makers. In the moral agent thinking rightly according to his principle of virtue, conscience will display the utilitarian principle. Similarly, there may be a variety of motives for adoption of a change in linguistic form or behavior: authority, ease of pronunciation, or distinctness from other utterances. The adoption of the change is what concerns natural selection. Natural selection shows the utility implicit unconsciously in selection by the agency of one of these motives (L 244). In commenting on moral behavior itself, Wright in effect based ethics on human nature, because of the importance he accorded to habit in human behavior: