The Occupational Hazard of the Fictional P.I.

"[Holmes does not even consider that a death narrated in The Hound of the Baskervilles could be an accident] because [that theory] does not jibe with his vision of the world and his desire to find murderers. It is just too commonplace for a man who dreams of grandiose crimes committed on deep, dark night under tragic circumstances."

-- from the chapter "Murder By Literature" in Sherlock Holmes Was Wrong.