For at least eight millennia, agricultural societies have regarded salt as a source of life and wealth, the origins of which are to be found in myths. The cross-disciplinary approaches of ethnologists, archaeologists, historians and environmentalists are now making it possible to profoundly renew our knowledge of the widespread exploitation of seawater, salt springs, salt lands and rock salt. Extraordinary techniques were used, while social logic placed salt at the centre of belief systems throughout the world. The twenty-four contributions in this book were presented in October 2006 at an international symposium marking the bicentenary of the death of Claude Nicolas Ledoux, the brilliant architect of the Royal Saltworks at Arc-et-Senans. Breaking with the boundaries between scientific disciplines and geographical divisions, the authors offer a new reading of the exploitation of salt by looking at the long term, from pre-Hispanic China and Mexico to prehistoric Europe, and from continental medieval salt works to ancient Mediterranean salt. It is therefore a question of technical and social history, in relation to environmental changes.