03 The Dewey Decimal scheme: playing by numbers

Now we can address the core problem, which is: how to arrange our non-fiction (the ‘subject-matter’) books in a meaningful manner. The basic premise is, of course, that we can identify one main subject of each book or report in our hands. Dewey has done half our job by listing out a thousand main subject names, starting not from 1, but 000, to 999, in a remarkably prescient manner which conforms neatly to the usual practice in our own computer age (all the numbers are 3-digit ones, hence can perfectly fitted into a fixed field in a database structure).

For the first round of classification, perhaps this is all that we will need to arrange our books subject-wise. Within each subject, naturally we will be arranging our books by the alphabetical ordering of author last-names, thus (Richard) Dawkins would come after (Charles) Darwin. If you had two books by Dawkins, you would arrange them by their date of (first) publication. These three fields: DDC three-digit code number, Author name, and Year, would suffice to order your books in a perfectly predictable sequence.

The whole structure depends on the expectation that any new subject could be ‘adjusted’ under these thousand heads. If you did have a subject that didn’t fit into a single one of them, of course you’d have a problem…then there would have to be a sufficient number of ‘empty’ numbers to cater to these eventualities. In practice, most subjects could be fitted as a sub-category under the thousand main categories provided by Dewey.

One great feature of this system is that if you walked into any library or looked up any catalogue that also followed the same classification scheme (the DDC in this case), you would expect to find your favourite books and authors in the same sequence. If you were interested in say Physics, you would zero in on the 500s; if in History and Geography, on the 900s. These are the Dewey 'hundreds', which bring together related subjects in groups. A little down the line, you will be glibly talking in numbers rather than in names. Unlike bookshops, where each manager devices an individual scheme of arranging the subjects, in academic and public libraries, all of them follow the same. This is spoilt to some extent by the fact that there are two or three main systems; fortunately, the second most common, the Universal Decimal Classification (UDC) closely follows the DDC, and the hundreds numbers are all quite similar.