The mineral sodium chloride — essential for human survival, one of the oldest trade commodities in the world, a driver of civilizational development across every inhabited continent, and a substance whose history illuminates how the most basic biological necessities become instruments of commerce, taxation, and political power.
Salt is the only rock we eat. Every human body requires it to survive — nerves fire, muscles contract, and cells maintain their fluid balance only with sodium chloride present. For most of human history, getting enough of it was not easy. Inland peoples traveled hundreds of miles to salt sources or traded for it at premium prices. Governments taxed it because everyone had to buy it. Wars were fought over it. Cities were built beside salt deposits. The word 'salary' comes from the Latin for salt — Roman soldiers were sometimes paid in it. Salt is boring until you think about what the world looked like before refrigeration, when it was the only way to preserve food through winter, and suddenly everything in premodern history looks different.