"penny for your thoughts"的定义和意义

What is the origin of the idiom "a penny for your thoughts" and when to use it?

The idiom "a penny for your thoughts" has its origins in medieval England and was first recorded in the 16th century. At that time, a "penny" was a small and common unit of currency. The phrase was used as a polite way to ask someone what they were thinking or to inquire about their thoughts or feelings. It is used to reflect a simple offer to pay a small sum for the privilege of knowing another person's thoughts, often used as a conversational ice-breaker.