What is the origin of the idiom "have a heart" and when to use it?

The idiom "have a heart" has its origins in ancient beliefs about the heart as the center of human emotion and compassion. In various cultures throughout history, the heart was associated with love, kindness, and empathy. This idea was reinforced by the physical sensations one feels in the chest area during strong emotional experiences. Over time, this cultural and physiological connection between the heart and compassion led to the idiomatic expression "have a heart," which means to show understanding, empathy, or mercy in a given situation. It is commonly used when asking for leniency, understanding, or assistance from another person.