worth your salt

The table next to my desk would have fit comfortably into an Enlightenment laboratory. One empty half-gallon jar sports a red lid with a small round hole in it. In the hole is a rubber cork with a hole in it. Standing in the cork is an air gap with a little water in it. Next to this contraption is another just like it, filled with sliced red onions and brine. Every few minutes, a bubble works its way through the fluid in the air gap. When the onions were at a livelier stage of pickling, it looked like the jar was at a low boil.

Behind these contraptions are more large jars sitting on plates. These jars are filled with shredded red and green cabbage and carrots, covered with whole cabbage leaves, weighed down with glass pickle stones, and submerged in brine.

Salt, we learned when we were small, was extremely precious in the ancient world. More precious than gold, it was used to pay Roman soldiers. Chinese emperors and the British in India controlled the populace by controlling the salt trade.

My parents and teachers didn't seem to know why salt was so precious. They talked a bit about how we need salt in our diet to replace what we lose when we sweat, and the need to cover up the flavor of rotten meat. Much later, I learned that salt was essential to preserve food, but it wasn't until I took up brine pickling for myself that I began to understand the place that salt had in the pre-20th century world.

If you harvest foodstuffs and leave them in their natural state, they become infested with fungal spores and aerobic bacteria and they rot. You can combat this with some foodstuffs by dehydrating them. Dehydration depends on dry weather or external sources of heat, and the foods become susceptible again as soon as they get wet. Salting meat before drying it helps with the dehydration and also helps protect from mold.

You can also pack the food with salt and keep it away from the air. You can pack the food in pots, barrels, baskets, or a lined hole in the ground. You can wrap it up tightly or just keep it topped up with brine. This keeps fungus and aerobic bacteria from getting to the food, allowing anaerobic bacteria to flourish. The anaerobic bacteria alter the food in various ways that we find pleasing, further discourage the growth of fungus and aerobic bacteria, and allow us to get through long winters and sea voyages. (Those who carried sauerkraut on sea voyages, like the Dutch, also avoided scurvy.) Before refrigeration, almost all of the ways that humans preserved food involved large quantities of salt.

If you didn't have salt, you couldn't preserve the food that you needed to get through the winter.

If you said a man wasn't worth his salt, you were saying that he (and his dependents) deserved to starve. It's like us saying that a person isn't worth the oxygen.

Thinking about this all, I was wondering how the Romans could afford to salt all the farmland around Carthage. Turns out that was a myth that originated in France several centuries later. At 20 tons of salt per acre, the Romans would have had to dedicate 3 years of economic output to buying the salt to render all Carthaginian farmland unproductive.

Sowing a small amount of salt in a small area in a captured city was a symbolic practice among some ancient peoples (although not the Romans). Scipio Africanus did plow up the ground where Carthage stood after razing it, and it is possible that he might have sowed a little bit of salt as part of a cursing ritual to keep the city from rising again. No contemporary source mentions salting the earth in Carthage, though, so it's unlikely that salt featured at all in the destruction of Carthage.

Even though this is well-known among historians now, this myth still appears as fact in children's textbooks.