The most difficult crime to track is the one which is purposeless.

Your life is not your own. Keep your hands off it.

My mind rebels at stagnation. Give me problems, give me work, give me the most abstruse cryptogram, or the most intricate analysis, and I am in my own proper atmosphere. But I abhor the dull routine of existence. I crave for mental exaltation.

"Dr. Munro, sir," said he, "I am a walking museum. You could fit what ISN'T the matter with me on to the back of a -- visiting card. If there's any complaint you want to make a special study of, just you come to me, sir, and see what I can do for you. It's not every one that can say that he has had cholera three times, and cured himself by living on red pepper and brandy."

Ex-Professor Moriarty of mathematical celebrity... is the Napoleon of crime, Watson.

In the year 1878 I took my degree of Doctor of Medicine of the University of London, and proceeded to Netley to go through the course prescribed for surgeons in the army. Having completed my studies there, I was duly attached to the Fifth Northumberland Fusiliers as Assistant Surgeon.

Detection is, or ought to be, an exact science, and should be treated in the same cold and unemotional manner.