The need to update historical study is generally recognized as essential to the progress of Wissenschaft des Judentums, the modern critical approach to Judaism. New questions arise, new sources are discovered, and conclusions reached in recent books and articles augment and alter what is contained in standard works. Gotthard Deutsch (1859-1921) was a German-trained Jewish historian who taught at the Hebrew Union College in Cincinnati beginning in 1891. He had been a student of the greatest Jewish historian of the nineteenth century, Heinrich Graetz (1817-1891), and owned a set of his multi-volume Geschichte der Juden. However, Deutsch realized that if he were to become a successor to Graetz, he had to update Graetz's work with the multiple new facts that had become known since Graetz published his history. So whenever Deutsch encountered a significant new source or study, he inscribed its essence into his interleaved copy of the relevant Graetz volume. For example, when Ludwig Geiger published a history of the Berlin Jewish community with passages relevant to the Reform movement, Deutsch added material from Geiger to update Graetz on the blank page opposite his treatment of the first permanent Reform synagogue, the Hamburg Temple.
