Sherlock Holmes remarked calmly... "Well, I have a trade of my own. I suppose I am the only one in the world. I'm a consulting detective, if you can understand what that means. Here in London we have lots of Government detectives and lots of private ones. When these fellows are at fault they come to me, and I manage to put them on the right scent. They lay all the evidence before me, and I am generally able, by the help of my knowledge of the history of crime, to set them straight. There is a strong family resemblence about misdeeds, and if you have all the details of a thousand at your finger ends, it is odd if you can't unravel the thousand and first."