The Frankfurt physician Georg Kloss (1787–1854) was an avid bibliophile and a Freemason. In 1835 his large collection of early printed books was sold by Sotheby's in London, as his extra-curricular interests had shifted from incunabula to the history of freemasonry. He went on to publish several scholarly books on the subject, of which this bibliography (Frankfurt, 1844) was the first. Mentioned by Frederick Leigh Gardner in 1911 as 'excellent though exceedingly scarce', it records over 5,000 books, documents and references relating to freemasonry. These date from 1723 to 1835, and many are very rare, having been printed in tiny quantities. Kloss's bibliography is organised thematically, with sections devoted to topics including Masonic history, ritual, rules and regional jurisdictions (notably France), and related movements including theosophy, kabbalah, the Templars and the Rosicrucians. It also contains indexes of lodges and of authors, translators and composers.