Changes in the mode of economic production must unquestionably be recognized as one of the chief factors entering into the historical process: the invention of new tools or machines, new ways of organizing work, new relationships of economic ownership, may have vast repercussions throughout the social order. Even racial differences may conceivably affect political and social organization. For that matter, still other circumstances can influence history—new types of armaments or ways of fighting, to take an important example, or shifts in religion and social beliefs.
