‘Tis the Seasoning
Before refrigeration, salt was so valuable as a food preservative that Roman soldiers were often paid with it or received allowance for it, and the word “salary” derives from “salarium,” the Latin word for salt allowance.
Hence, to be good at your job and worthy of your pay is to be “worth your salt.”
In the Sermon on the Mount, Jesus calls his audience “the salt of the earth.” By one interpretation, disciples were being called to preserve the earth from moral decay. By another reading, the listeners were being recognized for their value, like salt has. However, the salt found in Israel was rich in magnesium and hence very useful for stoking fires in ovens, so another interpretation is that the disciples were being told that they were essential in this sense. By another understanding, the term distinguished salt mined from the ground from that evaporated from the Dead Sea, which was more prone to contamination. There are many more interpretations. In modern usage, however, the term tends to mean honest, modest, and hardworking people.
The ocean is salty because of runoff water from land, seafloor vents and underwater volcanoes. Since rainwater is slightly acidic, it slowly dissolves rocks on land, the salty ions from which eventually flow into the ocean. Meanwhile, ocean water seeps into the crust below it and is heated by the Earth’s mantle, dissolving minerals from the crust which are added to seawater. A similar process occurs via the injection of salty ions from underwater volcanoes. And while there are different types of salt in nature, 85-90% of the dissolved ions in seawater are sodium and chloride, same as common table salt, which often comes from evaporated seawater.
To remind someone of an unpleasant fact is to “rub it in,” which itself is short for “rubbing salt in the wound.” Not surprisingly, doing this makes a wound more painful.
The superstition of curing bad luck by throwing salt over the left shoulder is itelf related to another salty superstition. In “The Last Supper,” da Vinci painted Judas Iscariot as having knocked the salt over with his elbow. Accordingly, spilled salt came to be associated with treachery and an invitation for the devil to corrupt the spiller. The cure was for the spiller was to throw salt over the left shoulder and blind the devil supposedly waiting there.
Four enormous hollowed-out underground salt caverns along the US Gulf Coast are filled with oil barrels. These create the country’s Strategic Petroleum Reserve, with a total capacity of 714 million barrels. After the Arab oil embargo of 1973-4, which cut off the country’s main source and led to shortages, the idea for the strategic stockpile came about.