human nature, which the average of experience in given races and at given stages of advancement has shown to be true within those limits.  There are places in his writings where he reluctantly admits that men are only moved by their interests, and he does not even take care to qualify this sufficiently.[264] But throughout the Social Contract we seem to be contemplating the erection of a machine which is to work without reference to the only forces that can possibly impart movement to it.

The consequence of this is that Rousseau gives us not the least help towards the solution of any of the problems of actual government, because these are naturally both suggested and guided by considerations of expediency and improvement.  It is as if he had never really settled the ends for which government exists, beyond the construction of the symmetrical machine of government itself.  He is a geometer, not a mechanician; or shall we say that he is a mechanician, and not a biologist concerned with the conditions of a living organism.  The analogy of the body politic to the body natural was as present to him as it had been to all other writers on society, but he failed to seize the only useful lessons which such an analogy might have taught him—­diversity of structure, difference of function, development of strength by exercise, growth by nutrition—­all of which might have been serviceably translated into the dialect of political science, and might have bestowed on his conception of political society more of the features of reality.  We see no room for the free play of divergent forces, the active rivalry of hostile interests, the regulated conflict of multifarious personal aims, which can never be extinguished, except in moments of driving crisis, by the most sincere attachment to the common causes of the land.  Thus the modern question which is of such vital interest for all the foremost human societies, of the union of collective energy with the encouragement of individual freedom, is, if not wholly untouched, at least wholly unillumined by anything that Rousseau says.  To tell us that a man on entering a society exchanges his natural liberty for civil liberty which is limited by the general will,[265] is to give us a phrase, where we seek a solution.  To say that if it is the opposition of private interests which made the establishment of societies necessary, it is the accord of those interests which makes them possible,[266] is to utter a truth which feeds no practical curiosity.  The opposition of private interests remains, in spite of the yoke which their accord has imposed upon it, but which only controls and does not suppress such an opposition.  What sort of control?  What degree?  What bounds?