The last department of ethics referred to--that which has to do with the origin and nature of moral sentiments and social customs--has a bearing on the question of the end of conduct in some respects more important than the investigation of ethical methods. For, whereas the latter expressly assumes certain ends as _primâ facie_ reasonable, the former inquiry, on the contrary, is now frequently understood to be able, without presupposing any ethical relations whatever, to trace the way in which, from primitive feelings and customs, morality itself has been evolved. The psychological side of ethical inquiry has always had an important place with English moralists. At times, indeed, the question of the "moral faculty" has excited so much interest as to divert attention from the nature of morality itself. Moral truth has been supposed to be something known and indisputable, the only question being how we came to know it. But the psychology of ethics, reinforced by the knowledge sociology gives of the development of morality, rises now to larger issues. It attempts to show the genesis of the moral from the non-moral, to account thus for the origin of ethical ideas, and even to determine what kinds of ends are to be striven after. In this way, a theory of the origin and growth of moral sentiments and institutions is made to render important help to more than one of the theories which will fall to be considered in the sequel. [Sidenote: 3. Present inquiry limited] [Sidenote: to theories depending on the human constitution,]