It is stupidity rather than courage to refuse to recognize danger when it is close upon you.

“How ever did you see that?” “Because I looked for it.”

I am the most incurably lazy devil that ever stood in shoe leather.

He [Professor Moriarty] is the Napoleon of crime, Watson. He is the organizer of half that is evil and of nearly all that is undetected in this great city. He is a genius, a philosopher, an abstract thinker. He has a brain of the first order.

A client is to me a mere unit, a factor in a problem.

I think there are certain crimes which the law cannot touch, and which therefore, to some extent, justify private revenge.

There is a danger there - a very real danger to humanity. Consider, Watson, that the material, the sensual, the worldly would all prolong their worthless lives. The spiritual would not avoid the call to something higher. It would be the survival of the least fit. What sort of cesspool may not our poor world become?