"[bark] at the moon" の定義と意味

What is the origin of the idiom "bark at the moon" and when to use it?

The idiom "bark at the moon" is originated from the behavior of dogs who bark at the moon, which is a futile and pointless activity since the moon is an inanimate object that cannot be affected by barking. The idiom is often used in a figurative sense, to describe someone who is pursuing a goal or engaging in an activity that is unlikely to succeed or to express a sense of frustration or disbelief at someone's behavior.