‘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.