Worth one’s salt
This expression usually appears in its negative form of not being worth one’s salt. It goes back to Roman times when salt was such a valuable commodity that it was synonymous with money. The Romans viewed salt as a shrewd investment. The expression first appears in the works of Gaius Petronius, who died c. 66 AD, when he wrote, “a man was not worth his salt”, meaning that he was not worth what he was paid. See also Salary.