The student of Ethics seeks to attain systematic and precise general knowledge of what ought to be, and in this sense his aims and methods may properly be termed ‘scientific’: but I have preferred to call Ethics a study rather than a science, because it is widely thought that a Science must necessarily have some department of actual existence for its subject-matter. And in fact the term ‘Ethical Science’ might, without violation of usage, denote either the department of Psychology that deals with voluntary action and its springs, and with moral sentiments and judgments, as actual phenomena of individual human minds; or the department of Sociology dealing with similar phenomena, as manifested by normal members of the organised groups of human beings which we call societies. We observe, however, that most persons do not pursue either of these studies merely from curiosity, in order to ascertain what actually exists, has existed, or will exist in time. They commonly wish not only to understand human action, but also to regulate it; in this view they apply the ideas ‘good’ and ‘bad,’ ‘right’ and ‘wrong,’ to the conduct or institutions which they describe; and thus pass, as I should say, from the point of view of Psychology or Sociology to that of Ethics or Politics. My definition of Ethics is designed to mark clearly the fundamental importance of this transition. It is true that the mutual implication of the two kinds of study--the positive and the practical--is, on any theory, very close and complete. On any theory, our view of what ought to be must be largely derived, in details, from our apprehension of what is; the means of realising our ideal can only be thoroughly learnt by a careful study of actual phenomena; and to any individual asking himself ‘What ought I to do or aim at?’ it is important to examine the answers which his fellow-men have actually given to similar questions. Still it seems clear that an attempt to ascertain the general laws or uniformities by which the varieties of human conduct, and of men’s sentiments and judgments respecting conduct, may be _explained_, is essentially different from an attempt to determine which among these varieties of conduct is _right_ and which of these divergent judgments _valid_. It is, then, the systematic consideration of these latter questions which constitutes, in my view, the special and distinct aim of Ethics and Politics.