"take something with a grain of salt"的定义和意义

What is the origin of the idiom "take something with a grain of salt" and when to use it?

The idiom "take something with a grain of salt" has its origins in ancient Roman and Greek traditions. The phrase was first recorded by the Roman author Pliny the Elder in his work "Naturalis Historia" and is derived from the Latin expression "cum grano salis." It suggests approaching information or claims with skepticism and not believing everything at face value.