From a drop of water a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other.

You have probably never heard of Professor Moriarty? said he.

I have seen too much not to know that the impression of a woman may be more valuable than the conclusion of an analytical reasoner.

It was so quiet, you could hear a pun drop.

For strange effects and extraordinary combinations we must go to life itself, which is always far more daring than any effort of the imagination.

As a rule, said Holmes, the more bizarre a thing is the less mysterious it proves to be. It is your commonplace, featureless crimes which are really puzzling, just as a commonplace face is the most difficult to identify.