A STEAM-ENGINE moves. The question is asked, How is it moved? A peasant answers, It is the devil moving it. Another man says, The steam-engine moves because the wheels are going round. A third maintains that the cause of the motion is to be found in the smoke floated from it by the wind.
The peasant's contention is irrefutable. To refute him some one must prove to him that there is no devil, or another peasant must explain that it is not a devil, but a German who moves the steamer. Then from their contradictory views they see that both are wrong. But the man who says the cause is the movement of the wheels refutes himself, seeing that having once entered on the path of analysis, he ought to proceed further and further along it; he ought to explain the cause of the wheels moving. And he has not to stop in his search for a cause till he finds the ultimate cause of the movement of the steam-engine in the steam compressed in the boiler. As for the man who explained the movement of the steam-engine as due to the smoke being blown back from it, he has simply noticed that the wheel explanation was insufficient, and pitching on the first accompanying symptom, gave that out as his cause.
The only conception which can explain the movement of the steamer is the conception of a force equal to the movement that is seen.
The only conception by means of which the movements of nations can be explained is a conception of a force equal to the whole movement of the nations.
Yet under this conception there are included by various historians forces of the most various kinds, and all unequal to the movement that is seen. Some see in it a force directly pertaining to heroes, as the peasant sees the devil in the steam-engine. Others, a force resulting from several other forces, like the movement of the wheels; a third class, intellectual influence, like the smoke.
So long as histories are written of individual persons—whether they are C?sars and Alexanders, or Luthers and Voltaires—and not the history of all, without one exception, all the people taking part in an event, there is no possibility of describing the movement of humanity without a conception of a force impelling men to direct their activity to one end. And the only conception of this kind familiar to historians is power.
This conception is the sole handle by means of which the material of history, as at present expounded, can be dealt with; and the historian who should, like Buckle, break off this handle, without discovering any other means of dealing with historical material, would only be depriving himself of the last chance of dealing with it. The necessity of the conception of the exercise of power to explain the phenomena of history is most strikingly shown by the very writers of universal history and the history of culture, who, after professedly rejecting the conception of power, inevitably resort to it at every step.
Historical science in relation to the questions of humanity has hitherto been like money in circulation—paper notes and metal coins. The historical memoirs and histories of separate peoples are like paper money. They may pass and be accepted, doing their part without mischief to any one, and even being useful, so long as no question arises as to their value. One has only to forget the question how the will of heroes produces events, and Thiers's histories will be interesting, instructive, and will, moreover, not be devoid of a certain poetry. But just as a doubt of the stability of paper money arises, either because from the ease of making it, too much is put into circulation, or because of a desire to replace it by gold, so a doubt of the real value of history of this kind arises either because too many such histories appear, or because some one in the simplicity of his heart asks: By what force did Napoleon do that?—that is, wishes to change the current paper for the pure gold of a true conception.
The writers of general history and the history of culture are like men who, recognising the inconvenience of paper money, should decide to make instead of paper notes, jingling coin of metal not of the density of gold. And such coin would be jingling coin, and only jingling coin. A paper note might deceive the ignorant; but coin not of precious metal could deceive no one. Just as gold is only gold when it is of value, not only for exchange, but also for use, so the writers of universal history will only prove themselves of real value when they are able to answer the essential question of history: What is power? These historians give contradictory answers to this question, while the historians of culture altogether evade it, answering something quite different. And as counters in imitation of gold can only be used in a community of persons who agree to accept them for gold, or who are ignorant of the true character of gold, so do the historians who do not answer the essential questions of humanity serve for some objects of their own as current coin at the universities and with that crowd of readers—fond of serious reading, as they call it.
农夫是驳不倒的。他已经想出了一个圆满的解释。要想驳倒他，就得有人向他证明没有鬼，或者另一个农夫向他解释，不是鬼，而是一个德国人在开动机车。直到发现矛盾百出，他们才知道他们两个都错了。但是，那个把轮子转动作为原因的人，可以把自己驳倒，因为只要他加以分析，就会想得更深、更深：他必须解释轮子转动的原因。在他没有找到锅炉里的蒸气压力是机车移动的最终原因的时候，他就没有停止探索原因的权利。那个用吹到后面的烟来解释机车移动的人，显然是这样的：他看出车轮转动不能作为原因，于是就把他看到的第一个迹象作为原因了。
唯一能够解释机车运动的概念，是与所见到的运动相等力量的概念。
唯一能够解释各民族运动的概念，是一种与各民族全部运动相等力量的概念。
不过，对这种概念，不同的史学家各有不同的理解，他们所理解的力量完全与所见到的运动力量不相等。有些人把它看作英雄们天赋的力量，犹如那个农夫以为机车里有鬼；另一些人把它看作由几种别的力量产生的力量，犹如车轮的运转产生了力量；又有一些人把它看作智力的影响，犹如被风吹走的烟。
只要历史所写的是个别的人物，不管这些个别的人是凯撒，是亚历山大，是路德，还是伏尔泰，而不是参加事件的所有的人——毫不例外的所有的人的历史，就不能不把迫使别人向着一定目标活动的力量归于个别的人。权力就是史学家所知道的这种唯一的概念。
这个概念是掌握现在所记述的历史材料的唯一的把柄，谁要是折断这个把柄，像保克尔那样，而又不懂得研究历史材料的其他方法，谁就只能使自己失去研究历史材料的唯一方法。用权力概念解释历史现象的必然性，由世界通史家和文化史家本身表示得最为明显，因为他们虽然表面放弃权力这个概念，而每迈出一步都得求助于它。
历史科学在对待人类的问题方面，至今仍然类似流通的货币——纸币和硬币。传记和专题民族历史好似发行的纸币。这种纸币可以供使用、可以供流通，在完成自己的使命时，对任何人都无害，而且还有益，只要不发生它是靠什么作保证的问题。只要把英雄们的意志是怎样产生事件的这个问题置于脑后，梯也尔之流的历史就会是饶有趣味的、富有教益的，也许还带有一点诗意。但是，正如由于纸币造得太容易，发行得过多，或者因为大家都要兑换黄金，于是钞票的真实价值就成问题一样，由于这类历史写得太多，或者由于有人幼稚地提出问题：“拿破仑究竟是靠什么力量做了这一手？”也就是想把通行的纸币换成实际理解的纯金的时候，这类历史的真正价值也就会引起疑问了。
世界通史家和文化史家正像那种人——他认识到纸币的缺点，决定用比黄金轻的金属铸成硬币来取代货币。那种硬币的确叮当作响，但也只是叮当作响而已。纸币还可以愚弄无知的人们；但是那种只能叮当作响而没有价值的硬币是欺骗不了任何人的。黄金之所以为黄金，是因为它不仅可以供交换，而且可以供使用，世界通史家也是这样，他们如能回答“权力是什么？”这个历史的主要问题，才算是真金。世界通史家对这个问题的回答矛盾百出，而文化史家则回避这个问题，环顾左右而言他。正如貌似黄金的筹码，只能在一些同意用它代替黄金的人们中间使用。或者在不知道黄金的性质的人们中间使用，不回答人类主要问题的世界通史家和文化史家们就是这样，他们不过是为了某种目的供给大学和那些爱读正经书本的读者中间流通的硬币。