At the beginning of 1778, a doctor from Vienna, Franz-Anton Mesmer, arrived in Paris where he set about expounding his rather exotic theory - according to him, the universe was swimming in a fluid which was responsible for occurences such heat, light, electricity and magnetism, but it was this fluid's relevance to medicine which he wished to highlight. In order to restablish health and man's harmony with nature he undertook strange healing sessions which became the origins of an extraordinary craze. Quickly, mesmerism became, in the hands of men like Nicolas Bergasse and Jacques-Pierre Brissot, a disguised political theory, close to that of Rousseau. In demonstrating the links of mesmerism to politics, and the scientific notions of the age, Robert Darnton provides in this work a decisive contribution to the study of the diffusion of ideas in French society at the end of the 18th century.

Robert Darnton is a professor at the University of Princeton in America, and a specialist in the history of European culture.