What is the origin of the idiom "call a spade a spade" and when to use it?

The idiom "call a spade a spade" originated from ancient Greece, with its earliest recorded use found in the works of the Greek philosopher Plutarch. The phrase has been traced back to his writings in the first century AD, where it was originally written in Greek as "to call a fig a fig and a trough a trough." The expression made its way into English in the 16th century, evolving into the form we use today. The idiom emphasizes straightforward and direct language, urging people to speak plainly and truthfully without euphemisms or beating around the bush.