The only conception that can explain the movement of the peoples is that of some force commensurate with the whole movement of the peoples.
Yet to supply this conception various historians take forces of different kinds, all of which are incommensurate with the movement observed. Some see it as a force directly inherent in heroes, as the peasant sees the devil in the locomotive; others as a force resulting from several other forces, like the movement of the wheels; others again as an intellectual influence, like the smoke that is blown away.
So long as histories are written of separate individuals, whether Caesars, Alexanders, Luthers, or Voltaires, and not the histories of all , absolutely all those who take part in an event, it is quite impossible to describe the movement of humanity without the conception of a force compelling men to direct their activity toward a certain end. And the only such conception known to historians is that of power.
This conception is the one handle by means of which the material of history, as at present expounded, can be dealt with, and anyone who breaks that handle off, as Buckle did, without finding some other method of treating historical material, merely deprives himself of the one possible way of dealing with it. The necessity of the conception of power as an explanation of historical events is best demonstrated by the universal historians and historians of culture themselves, for they professedly reject that conception but inevitably have recourse to it at every step.
In dealing with humanity’s inquiry, the science of history up to now is like money in circulation—paper money and coin. The biographies and special national histories are like paper money. They can be used and can circulate and fulfill their purpose without harm to anyone and even advantageously, as long as no one asks what is the security behind them.