For the moment, therefore, nearly all students of politics analyse institutions and avoid the analysis of man. The study of human nature by the psychologists has, it is true, advanced enormously since the discovery of human evolution, but it has advanced without affecting or being affected by the study of politics. Modern text-books of psychology are illustrated with innumerable facts from the home, the school, the hospital, and the psychological laboratory; but in them politics are hardly ever mentioned. The professors of the new science of sociology are beginning, it is true, to deal with human nature in its relation not only to the family and to religion and industry, but also to certain political institutions. Sociology, however, has had, as yet, little influence on political science. I believe myself that this tendency to separate the study of politics from that of human nature will prove to be only a momentary phase of thought, that while it lasts its effects, both on the science and the conduct of politics, are likely to be harmful, and that there are already signs that it is coming to an end. It is sometimes pleaded that, if thorough work is to be done, there must, in the moral as in the physical sciences, be division of labour. But this particular division cannot, in fact, be kept up. The student of politics must, consciously or unconsciously, form a conception of human nature, and the less conscious he is of his conception the more likely he is to be dominated by it. If he has had wide personal experience of political life his unconscious assumptions may be helpful; if he has not they are certain to be misleading. Mr. Roosevelt's little book of essays on _American Ideals_ is, for instance, useful, because when he thinks about mankind in politics, he thinks about the politicians whom he has known. After reading it one feels that many of the more systematic books on politics by American university professors are useless, just because the writers dealt with abstract men, formed on assumptions of which they were unaware and which they had never tested either by experience or by study. In the other sciences which deal with human actions, this division between the study of the thing done and the study of the being who does it is not found. In criminology Beccaria and Bentham long ago showed how dangerous that jurisprudence was which separated the classification of crimes from the study of the criminal. The conceptions of human nature which they held have been superseded by evolutionary psychology, but modern thinkers like Lombroso have brought the new psychology into the service of a new and fruitful criminology.