The mineral that built empires and sparked revolutions

Salt is so ordinary today that it is difficult to imagine it once mattered enormously to everyone. Mark Kurlansky's argument is that for most of human history, salt was among the most strategically important substances on earth — fought over, taxed, hoarded, and used to project political power across empires and continents. Its very ordinariness is a recent achievement, the product of industrial extraction and refrigeration that took centuries to develop and spread.

The reason for its former importance is biological necessity combined with historical scarcity. Before refrigeration, salt was the primary means of preserving food. Armies moved on salted meat and fish; cities depended on salted provisions to survive winter and siege. Control of salt production was effectively control of a society's ability to feed itself and sustain its military campaigns, which made salt deposits and salt-producing coastlines objects of intense and repeated political competition.

Kurlansky tracks the compound across history with real range. He describes the Roman roads built partly to move salt, the Venetian empire built substantially on the salt trade of the Adriatic, and the French gabelle — the salt tax — that was among the most resented elements of the ancien régime and helped build the resentments that fed the Revolution. Chinese salt monopolies stretched back more than two thousand years and required sophisticated administrative structures to maintain.

Gandhi's deliberate choice of salt as the focus of his 1930 campaign against British colonial rule was not at all accidental. The colonial government taxed salt and made its independent production illegal. By walking to the sea to make salt from seawater, Gandhi exposed the economic logic of colonialism through a substance so fundamental that every Indian family understood exactly what was being extracted from them and why.

The book is organised thematically and geographically as well as chronologically, with sustained digressions into the Basque fishing communities that salted cod for the entire Atlantic economy over centuries, the Himalayan salt routes that connected Tibet to the plains of India across some of the most difficult terrain on earth, and the salt merchants of New York who helped underwrite the early American economy. These digressions are not padding. They show how pervasively a single commodity can structure economic life across cultures and eras that had nothing else in common except the same fundamental biological need.

Kurlansky wrote Salt in 2002 after a similarly structured book about cod. Both demonstrate that the history of a single commodity can illuminate remarkable amounts of political, economic, and social history — more, sometimes, than a more conventional narrative approach would reveal, because the commodity keeps forcing connections across eras and geographies that conventional history separates. Kurlansky is not a professional historian, and that shows in the pleasure he takes in digression — a quality that serves the subject well and keeps the book readable from first page to last. These are qualities that serve the history of a commodity particularly well. Salt: A World History demonstrates that the history of a single commodity can illuminate far more political, economic, and social history than a conventional narrative approach would reveal.