As a rule, said Holmes, 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.

When a doctor does go wrong he is the first of criminals. He has nerve and he has knowledge.

[Sherlock Holmes:] The temptation to form premature theories upon insufficient data is the bane of our profession.

I have taken to living by my wits.

If the fresh facts come to our knowledge all fit themselves into the scheme, then our hypothesis may gradually become a solution. Sherlock Holmes speaking with Dr. Watson.

It is all in the way of professional experience.

We must look for consistency. Where there is a want of it we must suspect deception.