I bought the rock in the rundown hillside mining town of Cardona, Spanish Catalonia. It presented as an irregular, pink trapezoid. Curved indentations, etched by rain, marked its surface. The rock had a peculiar translucence and looked like a cross between rose quartz and soap. This resemblance to soap came because the stone dissolved in water. Rainwater wore its edges smooth, similar to a used bar of soap.
My rock followed its own rules. Friends often stopped by, and I told them the rock was salt. They would delicately lick a corner to verify its salty taste. Those who think a fascination with salt signals a bizarre obsession have simply never owned a rock like this.
The Essential Element
Salt is a chemical term for a compound resulting from the reaction of an acid with a base. Nature finds completion in these pairings. Acids search for a missing electron, while bases try to shed an extra one. Together, they form a well-balanced compound: a salt. In common table salt, the base, or electron donor, is sodium. The acid, or electron recipient, is chloride.
When sodium, an unstable metal that can suddenly burst into flame, reacts with chlorine, a deadly poisonous gas, the resulting staple food is sodium chloride, NaCl. Sodium chloride belongs to the only family of rocks eaten by humans.
Chloride remains essential for digestion and respiration. Without sodium, which the body cannot manufacture, the body becomes unable to transport oxygen or nutrients. It cannot transmit nerve impulses or move muscles, including the heart. An adult human contains approximately 250 grams of salt, enough to fill three or four standard saltshakers.
Salt content in an adult human - enough to fill 3-4 salt shakers
Far more than 101 uses for salt are documented. The modern salt industry often cites 14,000 uses. These applications include manufacturing pharmaceuticals, making soap, fertilizing agricultural fields, softening water, and dying textiles. Baby formula contains three distinct salts: sodium chloride, potassium chloride, and magnesium chloride.
A French folktale tells the story of a princess. She declares to her father, “I love you like salt,” angering him by the supposed slight. He banishes her from the kingdom. Only later, when denied salt, does he realize its intrinsic value. This realization proves the depth of his daughter’s love. Salt is inexpensive and easy to obtain today. From the beginning of civilization until about 100 years ago, however, salt was one of the most sought-after commodities in human history.
The Prehistoric Need
The search for salt has always challenged engineers across millennia. Salt production was one of Earth’s very first industries. Inevitably, salt also became the world’s first state monopoly. Trade routes that remain major thoroughfares today were established for salt. Salt secured empires and provoked revolutions.
The necessity for salt increased as humans moved away from carnivorous diets. Wild carnivores can meet their salt needs entirely by consuming meat. Wild herbivores, however, must forage for it. Humans hunting for salt often followed animal trails, since these always led to a brine spring, salt lick, or other reliable source.
The move to raise animals for meat, rather than killing wild ones, created an immediate need for salt. Domesticated animals need regular salt provisions. A horse requires five times the salt intake of a human.
Salt intake for a horse compared to humans
Salt intake for a cow compared to humans
Humans may have attempted animal domestication even before the Ice Age ended. They understood early that animals needed salt. People observed reindeer going to encampments because human urine provided a source of salt. Providing salt allowed humans to attract and eventually tame reindeer. Reindeer became a source of food but never achieved true domestication.
The formidable task of domesticating the large, fast, and powerful aurochs occurred around 6000 B.C. in Turkey or the Balkans. People turned these wild animals into cattle by controlling their diet, castrating the males, and corralling them into constricted spaces. Cattle quickly became a mainstay food, consuming huge quantities of both salt and grain. Once human diets adopted domestic animal meat, along with large portions of grains and vegetables, procuring salt became a necessity of life. This necessity immediately gave salt immense economic value and symbolic importance.
The Weight of Symbolism
Salt preserves food, acting as the principal preservation method until modern times. Egyptians used salt to mummify their dead. This ability to sustain life and protect against decay endowed salt with profound metaphorical importance. It became associated with permanence and longevity.
The ancient fascination with salt extended into the spiritual realm. The Greek poet Homer called salt a divine substance. Plato described it as especially dear to the Gods. Religious ceremonies, covenants, and magical charms often assigned high importance to salt.
Salt symbolized the binding of an agreement. Consequently, omitting a saltcellar on a Roman banquet table would have been interpreted as an unfriendly act and a reason for suspicion. At the table, salt might be served in a simple seashell at a plebeian’s meal. Patricians, however, used ornate silver saltcellars.
Medieval European etiquette prescribed careful handling of salt at the table. People were instructed to touch salt only with the tip of a knife, never by hand. In the sixteenth-century authority on Jewish law, The Prepared Table (Shulchan Arukh), it is explained that salt can only safely be handled using the middle two fingers. Serving salt with the thumb was believed to cause the death of one’s children. Using the little finger brought poverty. Using the index finger risked turning the server into a murderer.
Bread and salt, representing a blessing and its preservation, were often associated. Bringing bread and salt to a new home remains a Jewish tradition dating back to the Middle Ages. For centuries, the British dispensed with the bread. They carried only salt to a new home. In 1789, a procession of relatives escorted Robert Burns to his new house in Ellisland. They carried a bowl of salt.
The Psychological Fixation
The Welsh Jungian psychologist Ernest Jones, a friend of Sigmund Freud, published an essay in 1912 on the human obsession with salt. Jones found this fixation irrational and subconsciously sexual. He cited the curious Abyssinian custom of presenting a guest with a piece of rock salt. The guest would then lick it.
Jones asserted that “in all ages salt has been invested with a significance far exceeding that inherent in its natural properties”. He noted that this global importance demonstrates a general human tendency, not merely a local custom or notion.
Jones bolstered his argument with a reference to Freud. Freud had asserted in On the Psychopathology of Daily Life (Zur Psychopathie des Altagslebens) that superstitions result from attaching great significance to an insignificant object. This attachment occurs because the object is unconsciously associated with something else of great importance.
Jones concluded that all this attention to salt would be inexplicable unless people were truly thinking of more important things. Jones linked the primitive mind’s idea of salt, not only with that of semen, but also with the essential constituent of urine. Jones argued that the human unconscious associated salt, this seemingly trivial object, with permanence and longevity.
The Historical Crossroads
The history of salt stands at the forefront of the development of both chemistry and geology. It has created ingenious machines and some of the most bizarre engineering challenges. For millennia, engineers worked to move salt. A number of the greatest public works ever conceived were motivated by the need to transport this essential rock. Trade routes established for salt remain major thoroughfares. Alliances were built, revolutions provoked, and empires secured—all for a substance that fills the ocean, bubbles from springs, and thickly veins a large part of the earth’s rock. Salt’s role as the first great commodity defined the political and economic landscape of the ancient world.