churchmen are aware, and all Irishmen by facts which most Englishmen try to forget.  The student of politics must therefore read history, and particularly the history of those events and habits of thought in the immediate past which are likely to influence the generation in which he will work.  But he must constantly be on his guard against the expectation that his reading will give him much power of accurate forecast.  Where history shows him that such and such an experiment has succeeded or failed he must always attempt to ascertain how far success or failure was due to facts of the human type, which he may assume to have persisted into his own time, and how far to facts of environment.  When he can show that failure was due to the ignoring of some fact of the type and can state definitely what that fact is, he will be able to attach a real meaning to the repeated and unheeded maxims by which the elder members of any generation warn the younger that their ideas are ‘against human nature.’  But if it is possible that the cause was one of mental environment, that is to say, of habit or tradition, or memory, he should be constantly on his guard against generalisations about national or racial ‘character.’

One of the most fertile sources of error in modern political thinking consists, indeed, in the ascription to collective habit of that comparative permanence which only belongs to biological inheritance.  A whole science can be based upon easy generalisations about Celts and Teutons, or about East and West, and the facts from which the generalisations are drawn may all disappear in a generation.  National habits used to change slowly in the past, because new methods of life were seldom invented and only gradually introduced, and because the means of communicating ideas between man and man or nation and nation were extremely imperfect; so that a true statement about a national habit might, and probably would, remain true for centuries.  But now an invention which may produce profound changes in social or industrial life is as likely to be taken up with enthusiasm in some country on the other side of the globe as in the place of its origin.  A statesman who has anything important to say says it to an audience of five hundred millions next morning, and great events like the Battle of the Sea of Japan begin to produce their effects thousands of miles off within a few hours of their happening.  Enough has already occurred under these new conditions to show that the unchanging East may to-morrow enter upon a period of revolution, and that English indifference to ideas or French military ambition are habits which, under a sufficiently extended stimulus, nations can shake off as completely as can individual men.

CHAPTER V

THE METHOD OF POLITICAL REASONING