Whenever you overhear co-workers gossiping about someone, or read some salacious story on social media, it’s always best to take that information “with a grain of salt”. But why do we say that? What does sodium have to do with retaining a prudent amount of skepticism?
The saying first showed up in ancient Rome around 77 CE, in Pliny the Elder’s “Natural History” regarding a passage about Pompey (the guy best known for fighting with Julius Caesar). In it, he’d found directions for a mixture to inoculate himself against particular poisons. The recipe’s author, Mithridates VI, was a guy who’d intentionally ingest small doses of poison as a way to build up his own immunity, and his recipe called for various different ingredients that were supposed to be minced together before ultimately adding a grain of salt.
It’s not really clear how the phrase arrived at the meaning it has today. Some people have erroneously interpreted the salty story as a figurative warning. As in, “It’s best to be skeptical when you’re not totally sure that you’re not going to accidentally poison yourself anyway”. But, with no other indication that any other Romans of the time used the “grain of salt” idiom, it’s more likely that salt was an actual part of genuine recipe. It’s also possible that using salt to make poison easier to swallow may have just seemed like an appropriate way to describe exercising a bit of caution in the face of questionable information.
“Grain of salt” popped up again in 1647 in John Trapp’s Commentary on the Old & New Testaments, but it didn’t really catch on until the early 1900s after the journal The Athenaeum mentioned it in a 1908 issue: “Our reasons for not accepting the author’s pictures of early Ireland without many grains of salt.” By that point, the phrase had most likely become common enough for most readers to get the gist of its meaning. But, considering the large grey areas in the history of this particular phrase, I wouldn’t necessarily consider all of this a comprehensive origin story. So, I guess it might be best to “take it with a grain of salt”.
Got a Mundane Mystery you’d like solved? Send me a message via social media (@AndyWebbRadioVoice), or shoot me an email at firstname.lastname@example.org.
BROUGHT TO YOU BY: Airtron Heating & Air Conditioning