of growth which constitutes the history of society are to be found in the economic conditions of existence. From this he went on to socialism, which bases its militant philosophy upon this interpretation of history. But the truth or falseness of socialism does not affect the theory of history. In 1845 Marx wrote of the Young-Hegelians that to separate history from natural science and industry was like separating the soul from the body, and "finding the birthplace of history, not in the gross material production on earth, but in the misty cloud formation of heaven" (_Die heilige Familie_, p. 238). In his _Misere de la philosophie_ (1847) he lays down the principle that social relationships largely depend upon modes of production, and therefore the principles, ideas and categories which are thus evolved are no more eternal than the relations they express, but are historical and transitory products. In the famous _Manifesto of the Communist Party_ (1848) the theory was applied to show how the industrial revolution had replaced feudal with modern conditions. But it had little vogue, except among Socialists, until the third volume of _Das Kapital_ was published in 1894, when its importance was borne in upon continental scholars. Since then the controversy has been almost as heated as in the days of the Reformation. It is an exaggeration of the theory which makes it an explanation of all human life, but the whole science of dynamic sociology rests upon the postulate of Marx. The content of history always reflects the interests of the age in which it is written. It was so in Herodotus and in medieval chronicles. Modern historians began with politics. But as the complex nature of society became more evident in the age of democracy, the economic or sociological history gained ground. Histories of commerce and cities now rank beside those on war and kings, although there are readers still who prefer to follow the pennants of robber barons rather than to watch the slow evolution of modern conditions. The drum-and-trumpet history has its place like that of art, jurisprudence, science or philosophy. Only now we know that no one of these is more than a single glimpse at a vast complex of phenomena, most of which lie for ever beyond our ken.