Depend upon it, there is nothing so unnatural as the commonplace.

His incredible untidiness, his addiction to music at strange hours, his occasional revolver practice within doors, his weird and often malodorous scientific experiments, and the atmosphere of violence and danger which hung around him made him the very worst tenant in London.

There is no satisfaction in vengeance unless the offender has time to realize who it is that strikes him, and why retribution has come upon him.

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.

It is a capital mistake to theorize before you have all the evidence. It biases the judgment.

I think that I had better go, Holmes." "Not a bit, doctor. Stay where you are. I am lost without my Boswell.

The world is big enough for us. No ghosts need apply.