On glancing over my notes of the seventy odd cases in which I have during the last eight years studied the methods of my friend Sherlock Holmes, I find many tragic, some comic, a large number merely strange, but none commonplace; for, working as he did rather for the love of his art than for the acquirement of wealth, he refused to associate himself with any investigation which did not tend towards the unusual, and even the fantastic.

Do you know anything on earth which has not a dangerous side if it is mishandled and exaggerated?

Education never ends, Watson. It is a series of lessons, with the greatest for the last.

It is decreed by a merciful Nature that the human brain cannot think of two things simultaneously . . .

I have already explained to you that what is out of the common is usually a guide rather than a hindrance.

It is a mistake to confound strangeness with mystery. The most commonplace crime is often the most mysterious because it presents no new or special features from which deductions may be drawn. This murder would have been infinitely more difficult to unravel had the body of the victim been simply found lying in the roadway without any of those outré and sensational accompaniments which have rendered it remarkable. These strange details, far from making the case more difficult, have really had the effect of making it less so.

I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose.