Sir Arthur Conan Doyle was born on this date in 1859. Had there been no real-life writer named Conan Doyle, there would have been no fictional detective Sherlock Holmes. What would that absence have meant to the world of metaphors? As clumsy and convoluted as this is getting, diehard Sherlock Holmes fans may suspect where we're going: if there had been no Arthur Doyle, then the world would never have known the significance of the dog's not barking. (来源：专业英语学习网站 http://www.EnglishCN.com)

The silence of the watchdog, you may remember, was labeled "the curious incident of the dog in the night-time" by the fictional detective in Conan Doyle's short story Silver Blaze. The curiousness of that incident was that the watchdog remained silent while a valuable racehorse was supposedly being stolen from the stable. Sherlock Holmes then deduced the two-legged visitor to the stable must have been someone the watchdog already knew.

The popularity of the detective story—and the usefulness of that phrase—helped the phrase the dog that didn't bark develop its allusive sense referring to "a non-action or non-event which is significant precisely because it didn't happen."