The function of the historian is neither to love the past nor to emanci-pate himself from the past, but to master and understand it as the key to the understanding of the present. E. H. Carr 1961: 29 The twentieth century has been the century of revolution. Although the revolutionary model began with the eighteenth-century revolu-tions of North America and France, the nineteenth century was an era of failed revolution, and it was only in the current century that revolution swept the world-most notably in the revolutions of Mexico,
Joseph W. Esherick (1995) studied this question.