what the dog did in the night. A reference to the value of negative evidence or of paying as much attention to what is omitted as to what is included.

This is more of literary dog than a metaphorical dog, though the reference is sometimes used allusively. More properly this refers “To the curious incident of the dog in the night-time,” in A. Conan Doyle's tale “Silver Blaze.”

The iconic detective, Sherlock Holmes, tells the local inspector (who is investigating the theft of a race horse) that he should attend to this incident. The inspector replies, “The dog did nothing in the night-time,” to which Holmes replies, “That was the curious incident.” The information that our astute observer gleaned from this “incident” is that, since the dog did not bark, the thief must have been known to the dog. Therefore, the theft was an inside job. When called upon, this allusion reminds us that negative information may be as significant as that which is affirmative. Whether this accurately reflects the true nature of dogs is not necessarily clear, though the assumption that dogs bark at strangers is apparently common knowledge. Stephen Budiansky, in his exposé, The Truth About Dogs, suggests that it may not always be true.

Just as this is a literary dog in origin, so too does it seem to turn up more often in literature than in the news or everyday speech. It is most likely to be cited by those who see themselves in the tradition of popular writing that Doyle influenced. Robert Heinlein calls on it in more than one instance, but most closely in his satire of sword and sorcery novels, Glory Road . The lady's champion, Oscar, unknowingly commits a faux pas on a foreign planet when he does nothing in the night with his host's wife and daughters. Typical American, Oscar thinks that his host would be offended, and our hero doesn't get that the lord of the manor is hoping that he will provide stud services. The error comes to light when Oscar ruefully tells his groom, Rufo, that “the dog did nothing in the night.” Fortunately, the hero is able to make up for lost time, evoking, perhaps the more promiscuous associations with dogs.