“Tell him next, that crimes cause their own detection. There's another bit of copy-book morality for you, Fosco. Crimes cause their own detection. What infernal humbug!”

“We tell stories of other people's marriages, Detective Hastroll thought. We are experts in their parables and parabolas. Be can we tell the story of our own. If we could, Hastroll thought, there might be no murders. If we could, we might avoid our own cruelties and crimes.”

“The work of the philosophical policeman," replied the man in blue, "is at once bolder and more subtle than that of the ordinary detective. The ordinary detective goes to pot-houses to arrest thieves; we go to artistic tea-parties to detect pessimists. The ordinary detective discovers from a ledger or a diary that a crime has been committed. We discover from a book of sonnets that a crime will be committed. We have to trace the origin of those dreadful thoughts that drive men on at last to intellectual fanaticism and intellectual crime. We were only just in time to prevent the assassination at Hartlepool, and that was entirely due to the fact that our Mr. Wilks (a smart young fellow) thoroughly understood a triolet.”

“There are no crimes and no criminals in these days. What is the use of having brains in our profession? I know well that I have it in me to make my name famous. No man lives or has ever lived who has brought the same amount of study and of natural talent to the detection of crime which I have done. And what is the result? There is no crime to detect, or, at most, some bungling villainy with a motive so transparent that even a Scotland Yard official can see through it.”

“There must be some connection between the general nullity of Christie's prose and the tendency of her detectives to take Jewishness as a symptom of crime.”

“If guns cause crime, all of mine are defective. ”