The Ancient Origins Behind The Phrase 'Grain Of Salt'

You've probably ended a story before with the cautionary phrase "take it with a grain of salt." Maybe you heard that from a friend who was relaying gossip or shocking details that may not be accurate. The term means that you should take the information with reservation or skepticism, as Merriam-Webster puts it. 

More likely than not, that seven-word idiom is in your everyday vocabulary, yet the origin of the phrase may be an afterthought. In fact, instead of "grain of salt," you probably swapped it out for a "pinch of salt" at times. We all may know that adding a literal pinch of salt can elevate a dish, but the proverbial term means the same as "grain of salt" — it's just more commonly used in Britain, per Cambridge Dictionary.

Why do we advise people to take something with a "grain of salt" instead of a "pinch of pepper" or "slice of pizza?" We're spilling the beans on the two possible ancient origins of this common phrase.

The idiom "grain of salt" did not start out as an idiom. It's believed to have first originated in "Naturalis Historia" ("Natural History" in Latin) written by Pliny the Elder (via Voice of America). Pliny, a Roman author and naturalist, published "Naturalis Historia" in 77 AD. It was an encyclopedia that covered topics ranging from anthropology and botany to physiology and zoology.

The term "grain of salt" appeared in a passage about an antidote for poison (via Perseus Digital Library). If you're curious enough to try the antidote, it calls for two dried walnuts, two figs, 20 leaves of rue, and a literal grain of salt. How did this phrase turn into an idiom alluding to skepticism? Etymologist Michael Quinion suggests the phrase may have been misinterpreted as a figurative term (via World Wide Words).

Another possible origin of the figurative phrase also has to deal with poison. It was believed that a Roman general tried to build immunity to poison by self-administering small amounts of poison. To help ingest the poison, he was said to take the poisons with a grain of salt (via Mental Floss). However, you may want to take that origin story with a grain of salt.

Although the idiom "grain of salt" originated in the first century, it didn't appear in the English vernacular until 1647 (via How Stuff Works). John Trapp, an English bible commentator used the phrase in "Commentary on the Old and New Testaments."

It wasn't until 1908 that the proverbial expression Americans know today appeared again. The phrase popped up in the literary journal "The Athenaeum." Per How Stuff Works, it was used to inflict skepticism about the qualities of photos a photographer took in Ireland. As mentioned, Britons commonly used the expression "pinch of salt" instead of "grain of salt." According to History Extra, the idiom was used in "Cicero & the Roman Republic," a book about the Roman Empire by F.R. Cowell.

The idiom went through several iterations throughout centuries before it took on the meaning it is known for today. When telling the origin of the popular phrase, it's up to you whether to warn the skeptics to take it with a "grain of salt."