What is the origin of the idiom "an eye for an eye" and when to use it?

The idiom "an eye for an eye" originated from the ancient code of Hammurabi, a set of laws in Babylonian civilization. This principle, known as lex talionis, states that punishment should be proportional to the harm inflicted. The expression is now used to signify the concept of seeking retribution or justice in a manner that mirrors the offense committed against oneself. In other words, it implies a desire for fairness and retaliation, often used to emphasize the idea of reciprocal punishment.