The writing of history becomes ever more difficult. The power of God or the weakness of man, Christianity or the divine right of kings to govern wrong, can easily be made responsible for the downfall of states and the birth of new societies. Such elementary conceptions lend themselves willingly to narrative treatment and from Tacitus to Macaulay, from Thuycidides to Green, the traditionally famous historians have been more artist than scientist: they wrote so well because they saw so little. To-day by a natural reaction we tend to a personification of the social forces, great men being merely or nearly instruments in the hands of economic destiny. As so often the truth does not lie in between. Great men make history, but only such history as it is possible for them to make. Their freedom of achievement is limited by the necessities of their environment. To portray the limits of those necessities and the realisation, complete or partial, of all possibilities, that is the true business of the historian.