'Internationally known for his work on the role played by the crowd theory in the origins of sociology, particularly in France at the end of the nineteenth century (The Politics of Crowds: An Alternative History of Sociology, Cambridge, 2012), Christian Borch, in this new book, develops a critical reinterpretation of this tradition which brought him to build a completely original conceptual apparatus. One of the interests of this frame is to render again social sciences attentive to the plasticity and uncertainty of social processes. Its empirical implementation sheds a new light on crucial and misunderstood aspects of our modernity, particularly in the financial sphere. An important book that will trigger new debates in social sciences.' Luc Boltanski, School for Advanced Studies in the Social Sciences, Paris