The larger crimes are apt to be the simpler, for the bigger the crime, the more obvious, as a rule, is the motive.

Really, Watson, you excel yourself," said Holmes, pushing back his chair and lighting a cigarette. "I am bound to say that in all the accounts which you have been so good as to give of my own small achievements you have habitually underrated your own abilities. It may be that you are not yourself luminous, but you are a conductor of light. Some people without possessing genius have a remarkable power of stimulating it. I confess, my dear fellow, that I am very much in your debt.

...it is only when a man goes out into the world with the thought that there are heroisms all round him, and with the desire all alive in his heart to follow any which may come within sight of him, that he breaks away... from the life he knows, and ventures forth into the wonderful mystic twilight land where lie the great adventures and the great rewards.

I could not rest, Watson, I could not sit quiet in my chair, if I thought that such a man as Professor Moriarty were walking the streets of London unchallenged.

When you have one of the first brains of Europe up against you, and all the powers of darkness at his back, there are infinite possibilities.

I am somewhat exhausted; I wonder how a battery feels when it pours electricity into a non-conductor?

The world is full of obvious things which nobody by any chance ever observes.