Take It With a Grain of Salt

Traces to the Roman writer Pliny the Elder, who in 77 AD recorded an ancient poison antidote recipe, made from walnuts, figs, and rue leaves, to "be taken fasting, plus a grain of salt." The salt likely just made the unpleasant remedy easier to swallow, literally. The figurative sense, treating a claim or story with a pinch of skepticism rather than swallowing it whole, developed much later among classically educated scholars and is recorded in English from 1647.