Streams may spring from one source, and yet some be clear and some be foul.

You know my powers, my dear Watson, and yet at the end of three months I was forced to confess that I had at last met an antagonist who was my intellectual equal. My horror at his crimes was lost in my admiration at his skill.

It is a capital mistake to theorize before one has data.

Is it not? Is it not? Breadth of view, my dear Mr. Mac, is one of the essentials of our profession. The interplay of ideas and the oblique uses of knowledge are often of extraordinary interest.

One should always look for a possible alternative and provide against it. It is the first rule of criminal investigation.

A little monograph on the ashes of one hundred and forty different varieties of pipe, cigar, and cigarette tobacco.