I mentioned in many of the stories the commonplace books in which Holmes docketed items of information for later use.

In The Veiled Lodger, he “threw himself with fierce energy upon the pile of commonplace books in the corner. For a few minutes there was a constant swish of the leaves, and then with a grunt of satisfaction he came upon what he sought. So excited was he that he did not rise, but sat upon the floor like some strange Buddha, with crossed legs, the huge books all round him, and one open upon his knees.”

Commonplace books are scrapbooks filled with all manner of odds and ends of information, used as an aid for remembering useful facts, and are unique to the individual that compiles them.

Anyone looking at any one of Holmes commonplace books would see what his particular tastes and interests were. He compiled each one neatly from rough notes and cuttings, recompiling them occasionally, and preserving them with care and devotion.

In the modern world, blogs might be seen as the equivalent of the commonplace book, but they are more akin to journals or diaries as the entries are in date order rather than being random notes and jottings.

Douglas Johnston on the D*I*Y Planner website (and also I may note, a Sherlockian as evidenced by his excellent A Study in Sherlock – sadly, no longer maintained), has produced a two-part article on the commonplace book.

Part I deals with their origins and uses and Part II suggests ways of setting up a modern equivalent using paper (the Moleskine range is my favourite) or in digital format. The D*I*Y Planner website is an excellent place to read about notebooks, pens, etc.