Juliet and Dan went to Thailand one year. When she returned, she showed me her pictures and several were of a salt mine. Pyramids of salt set in rows stretched to the horizon. Workers were scattered throughout the mine. Seawater flowed in and was then trapped by small dikes. Evaporation, aided by a blazing sun and a windmill, occurred and workers raked the salt into the waist-high pyramids. This salt mine stretched more than a quarter mile to the sea, a series of rectangles dotted with salt piles set in neat rows. When evaporation was complete, workers shoveled and scooped the islands of dried salt into wheelbarrows and pushed them through the shallow water for further processing. This is how salt has been mined for at least eight thousand years.

Salt is crucial to our very lives as it’s one of our electrolytes and necessary to regulate the water content of our bodies. Ironically, it can also be a case of too much is a bad thing, because excess salt adds to high blood pressure. And even though it’s crucial for animals, it’s toxic to many land plants.

We’re equipped to detect salt with the taste receptors in our mouths, which partly explains why it is our most popular seasoning. And, equally vital, particularly before refrigeration, canning, and freezing, was its use as a preservative, especially for meats.

Thus, since prehistoric times, people have devoted lots of time to obtaining this necessary and important chemical. It was used in ancient Egypt for embalming and also for salted fish and birds traded around the Mediterranean. Salt caravans crossing the Sahara were operated by the Tuareg from ancient times until 1960. Roman soldiers were sometimes paid in salt, giving rise to the words salary and soldier. And the word salad literally means salted, the culinary practice of salting leafy vegetables. Venice ushered in the Renaissance not because of its manufacture of salt but by trading it. Mahatma Gandhi led a protest march against taxes levied by British rulers on the export of salt. The march brought millions of people together as one and was pivotal to Indian independence.

Sea salt from different areas has varied flavors. Table salt comes from the mass production of salt, often from underground deposits, refined in small grains. Like the salt mine Juliet saw, the manufacture and production of salt is one of our earliest chemical industries. Iodine is added to salt because it’s lacking in some diets. And salt is treated to pour easily in spite of moisture. I vividly remember as a little girl staring at the drawing of the little girl holding a box of salt that contained the same picture of a little girl holding a box of salt to an imperceptible miniaturized perpetuity. Above her head blazed the slogan, When it rains, it pours. The drawing allowed me to contemplate infinity as I wondered at the increasingly tiny pictures.