Perhaps it will be said that the chess-players have a common purpose, and the players in life's game have none. The reply is that science assumes they have; science assumes that they play to win in the struggle for existence; and only on the assumption that men have common purposes is it possible to frame any scientific account of their actions. The science of Political Economy assumes that it is a common purpose of men to acquire wealth, and that their actions are determined by that purpose. It then goes on to show that if that is their purpose, then the conditions under which it can be and is effected are of a certain kind, _e.g._ men must buy in the cheapest and sell in the dearest market. It is not necessary to assume, nor does Political Economy assume, that man can only purpose to acquire wealth, or that he must under all circumstances do so. In the same way it is wholly unscientific in sociology to assume that success in the struggle for existence is either a thing that man must aim at, or the only thing that he can aim at: the soldier dies for his country, the martyr for his faith. The institutions of a nation--legal, political, social, and religious--express the predominant purposes for which successive generations of the community have laboured; and the evolution of mankind is the history of the various degrees of success with which men have realised the ideals which they have purposed to attain. The successive reforms by which progress has been effected have all been purposed, and have all been purposed by men who believed, rightly or wrongly, that in so doing they were serving God and their fellow-men, and that the ideals of truth, justice, equality, fraternity, love, compassion, and mercy express God's will and the Divine purpose.