Book excerpt: In his book on constitutional revolutions in the Ottoman Empire and Iran in the early twentieth century, Nader Sohrabi considers the global diffusion of institutions and ideas, their regional and local reworking and the long-term consequences of adaptations. He delves into historic reasons for greater resilience of democratic institutions in Turkey as compared to Iran. Arguing that revolutions are time-bound phenomena whose forms follow global models in vogue at particular historical junctures, he challenges the ahistoric and purely local understanding of them. Furthermore, he argues that macro-structural preconditions alone cannot explain the occurrence of revolutions, but global waves, contingent events and the intervention of agency work together to bring them about in competition with other possible outcomes. To establish these points, the book draws on a wide array of archival and primary sources that afford a minute look at revolutions' unfolding.