Violence does, in truth, recoil upon the violent, and the schemer falls into the pit which he digs for another. - Arthur Conan Doyle

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.

To the logician all things should be seen exactly as they are, and to underestimate one's self is as much a departure from truth as to exaggerate one's own powers. When I say, therefore, that Mycroft has better powers of observation than I, you may take it that I am speaking the exact and literal truth.

The more outre and grotesque an incident is the more carefully it deserves to be examined, and the very point which appears to complicate a case is, when duly considered and scientifically handled, the one which is most likely to elucidate it.