> Belling the Cat is a fable ... In the story, a group of mice agree to attach a bell to a cat's neck to warn of its approach in the future, but they fail to find a volunteer to perform the job. The term has become an idiom describing a group agreeing to perform an impossibly difficult task.
Of course a quick web search answers your question. The fable is that all the mice would like to have the cat wear a bell, but despite the obvious benefits, there are no volunteers for the dangerous task.
> Belling the Cat is a fable ... In the story, a group of mice agree to attach a bell to a cat's neck to warn of its approach in the future, but they fail to find a volunteer to perform the job. The term has become an idiom describing a group agreeing to perform an impossibly difficult task.