تعریف و معنای "get blood from a stone"

What is the origin of the idiom "get blood from a stone" and when to use it?

The idiom "get blood from a stone" is used to describe a situation where it is extremely difficult or impossible to obtain something, typically referring to extracting information, money, or any valuable resource from someone who does not possess or unwilling to give it. The origin of this expression is uncertain, but it dates back to at least the 17th century. The idea behind the idiom is that stones and turnips are lifeless and do not contain blood, making it useless to try to extract something from them.