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

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

It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.

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

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.