“It is a mistake to confound strangeness with mystery. The most commonplace crime is often the most mysterious because it presents no new or special features from which deductions may be drawn. This murder would have been infinitely more difficult to unravel had the body of the victim been simply found lying in the roadway without any of those outré and sensational accompaniments which have rendered it remarkable. These strange details, far from making the case more difficult, have really had the effect of making it less so.”

“The most common place crime is often the most mysterious, because it presents no new or specific features from which deductions may be drawn”

“As a rule, the more bizarre a thing is the less mysterious it proves to be. It is your commonplace, featureless crimes which are really puzzling, just as a commonplace face is the most difficult to identify.”

“Presentiments are strange things: and so are sympathies; and so are signs; and the three combined make one mystery to which humanity had not yet found the key.”

“Too much mercy... often resulted in further crimes which were fatal to innocent victims who need not have been victims if justice had been put first and mercy second.”

“Unlike him I had been unable to escape into the simple complexities of science. All he had to do was solve the mystery of the universe, which may be difficult but is not as difficult as living an ordinary life...(How happy scientists are! Why didn't we become scientists, Percival? They confront problems which can be solved. We don't know what we confront. Does it have a name?)”