In a Sherlock Holmes short story Silver Blaze, a murder of a racehorse trainer and a theft of a racehorse occur. Investigating the scene of the crime, Holmes asks those involved in the case, “Was there anything unusual about the night?”
All those involved answer, “There was nothing unusual that happened.”
Holmes asks another question, “Then, what about the dog that night?”
Then, everyone says, “The dog was quiet.”
Holmes responded, “Isn’t that unusual?”
Dogs are supposed to bark and alert the family if there is an intruder, and the fact that the dog did not bark that night was certainly unusual. Holmes reached the conclusion that the crimes were committed by someone who the dog was familiar with. Holmes ...