A historian is sometimes forced to read books published several decades, in some case even centuries back, in order to tease out information that is relevant. Antony Grafton, in hisThe Footnote: A Curious History has drawn attention to this rather interesting aspect of historical research. Unlike other strands of knowledge in which one can see a cumulative increase in human understanding, in historical research there is search for new quetions about the past and new ways of understanding and rep...