It is the business of politics, the art of the statesman, to prescribe to the practitioners of all other arts and professions the lines on which and the conditions under which they shall exercise their vocation with a view to securing the supreme practical end, the well-being of the community. Among the other professions and arts which make the materials the statesman employs, the profession of the educator stands foremost. The statesman is bound to demand certain qualities of mind and character in the individual citizens. The production of these mental and moral qualities must therefore be the work of the educator. It thus becomes an important branch of politics to specify the kind of mental and moral qualities which a statesman should require the educator to produce in his pupils. It is this branch of politics which Aristotle discusses in his _Ethics_. He never contemplates a study of the individual’s good apart from politics, the study of the good of the society. What then is the good or the best kind of life for an individual member of society? Aristotle answers that as far as the mere name is concerned, there is a general agreement to call the best life, _Eudaimonia_, Happiness. But the real problem is one of fact. What kind of life deserves to be called happiness? Plato had laid it down that the happy life must satisfy three conditions. It must be desirable for its own sake, it must be sufficient of itself to satisfy us, and it must be the life a wise man would prefer to any other. The question is, What general formula can we find which will define the life which satisfies these conditions? To find the answer we have to consider what Plato and Aristotle call the work or function of man. By the work of anything we mean what can only be done by it, or by it better than by anything else. Thus the work of the eye is to see. You cannot see with any other organ, and when the eye does this work of seeing well you say it is a good eye. So we may say of any living being that its work is to live, and that it is a good being when it does this work of living efficiently. To do its own work efficiently is the excellence or virtue of the thing. The excellence or virtue of a man will thus be to live efficiently, but since life can be manifested at different levels, if we would know what man’s work is we must ask whether there is not some form of life which can _only_ be lived by man. Now the life which consists in merely feeding and growing belongs to all organisms and can be lived with equal vigour by them all. There is, however, a kind of life which can only be lived by man, the life which consists in conscious direction of one’s actions by a rule. It is the work of man to live this kind of life, and his happiness consists in living it efficiently and well. So we may give as the definition of human well-being that it is "an active life in accord with excellence, or if there are more forms of excellence than one, in accord