It is of the highest importance in the art of detection to be able to recognise out of a number of facts which are incidental and which are vital.

My name is Sherlock Holmes. It is my business to know what other people do not know.

One forms provisional theories and waits for time or fuller knowledge to explode them. A bad habit, Mr. Ferguson, but human nature is weak. Sherlock Holmes speaking with Dr. Watson.

He had never seen a woman doctor before, and his whole conservative soul rose up in revolt at the idea. He could not recall any biblical injunction that the man should remain ever the doctor and the woman the nurse, and yet he felt as if a blasphemy had been committed.

That which is clearly known hath less terror than that which is but hinted at and guessed.

An absence of antecedents and of relatives is sometimes an aid rather than an impediment to social advancement . . .

To let the brain work without sufficient material is like racing an engine. It racks itself to pieces.