David A. Bell is Sidney and Ruth Lapidus Professor of History at Princeton, and a contributing editor for The New Republic. 

As the paperless future approaches, certain sorts of publications have inevitably moved into the all-digital realm faster than others. Most of us still prefer paper when it comes to beach novels, for instance, or the cherished volumes of our personal libraries. At the other extreme, scientific journals effectively went all-digital years ago, and thanks to GPS, maps and road atlases are quickly following. Last week saw another milestone: the symbolic funeral of paper encyclopedias, with the inevitable announcement that the Encyclopedia Britannica is ceasing print publication.

Encyclopedias, along with other reference works, would seem particularly obvious candidates for digitization. Paper encyclopedias are large, heavy, and expensive ($1,395 for the final print edition of Britannica). They are nowhere near as easily and thoroughly searchable as their digital counterparts. They cannot be easily updated, still less constantly updated. And they are far more limited in size. The 2002 Britannica contained 65,000 articles and 44 million words. Wikipedia currently contains close to four million articles and over two billion words (this information comes, of course, from Wikipedia)....

But the great paper encyclopedias of the past had other, grander ambitions: They aspired to provide an overview of all human knowledge, and, still more boldly, to put that knowledge into a coherent, logical order. Even if they mostly organized their articles alphabetically, they also sought ways to link the material together thematically—all of it. In 1974, for instance, the editors of the Encyclopedia Britannica added to the work a one-volume “Propaedia,” which sought to provide a detailed outline of human knowledge, while referencing the appropriate articles of the encyclopedia itself. Large headings such as “Life,” “Society,” and “Religion” were subdivided into forty-odd “divisions” and then further into hundreds of individual “sections.”...