Social evolution is discussed on two different levels in Marx's writings. In The German Ideology, the Preface to The Critique of Political Economy and elsewhere, Marx attempted to account for the broad sweep of human history from the pre-class societies of the distant past to the post-class societies of the future. A second theoretical concern of Marx's was to grasp the direction of evolution in capitalism and the mechanisms underlying this evolution. These two areas of investigation are obviously connected; capitalism is a part of human history. Nonetheless, it is possible to consider historical developments in capitalism on their own terms, apart from their place in the grand scheme of human history. And it is possible to ask whether evolution in capitalism enables a transition to socialism without invoking transhistorical principles.