The preparation of thematic catalogs of a composer’s works became increasingly popular in the 19th century at the same time that publication of collected works editions became more common. Franz Hauser, one of the founding members of the Bachgesellschaft, possessed one of the most extensive collections of Bach manuscripts in private hands. During the 1830s he began work on a thematic catalog of the works of Bach, the first such effort and one of the first catalogs of any kind of Bach’s works; however, his catalogs were never published. The displayed page shows the first of the church cantatas, listed in alphabetical order. Each entry catalogs the opening musical incipit, the title and instrumentation, as well as the location of the original manuscript score in Bach’s hand, if known, and the publisher of the first printed edition. Multiple hands and layers of annotations in the catalog indicate that information was updated as locations of autograph manuscripts changed or became known.