I am an expert on everything in the culinary world.
You may want to take that with a grain of salt, because, if you believe it, I’ve got some ocean front property in Arizona you may like.
In the previous sentence, you may understand the allusion in latter idiom without explanation. Arizona does not border any oceans; it’s land-bound. Therefore, if you believe I have such property, you’d believe anything. But, why should you take the statement about my expertise with a ‘grain of salt?’ You may understand that I mean that you should be skeptical and not necessarily believe me, but why a grain of salt? Why do we use this expression and to what does it allude?
There are many salt-related expressions in the English language, and in most other languages. There are also many superstitions about salt. The importance of salt in the ancient world gave rise to the expression worth your salt, for example. You may also be familiar with the superstition that spilling salt is bad luck. And, a very good and honest person might be called the salt of the earth. The expression ‘take something with a grain of salt’ undoubtedly has something to do with the importance of salt, just like most other salt-related expressions.
Some scholars think that the idiom began in Roman times, coming from the Latin cum grano salis, attributed to Pliny the Elder. Pliny, in Natural History, from the first century BC, told a tale about Pompey who discovered a poison antidote that involved fasting and the addition of a grain of salt (addito salis grano). So, the modern idiom, according to this theory, came from the idea that a grain of salt protected on from poison, which transferred eventually to protecting one from undue acceptance misinformation or untrue, misleading, or exaggerated statements. In English, this idiom appears in print as early as the 1600’s.
It is also popular that the original intention was not to figurative invoke protection, but seasoning. That is, a grain of salt is all it takes to improve the flavor of food and make it go down a bit easier. So, the allusion may have originally been to making untruthful statements “easier to swallow.”
The latter theory is the most likely candidate, aligning with the view of salt as a protective, owing to its preservative qualities.
Usually, this expression is not a way of saying that something is an outright lie, but rather that it is exaggerated or only partly correct. So, for example, if you take with a grain of salt my statement that I am an expert on everything in the culinary world, you wouldn’t assume I knew absolutely nothing, but that I was somewhat, or much less, than an expert.
Sources
1. Ammer, Christine. Fruitcakes & Couch Potatoes, and Other Delicious Expressions. Plume, 1995.
2. Ratcliffe, Susan. Oxford Treasury of Sayings and Quotations. Oxford University Press, 2011.
3. Heacock, Paul. Cambridge Dictionary of American Idioms. Cambridge: Cambridge UP, 2010.