In the seventeenth century several bibliographies of bibliographies were undertaken as independent enterprises. One of them was actually completed and published and after several editions had the good fortune to be revised and to receive a supplement. A century after Gesner had published his bibliographies of authors and subjects, in the decade between 1643 and 1653, Jodocus a Dudinck, who did not fulfill his promise, and Philip Labbé, sought to survey all scholarship and hit upon the idea of a bibliography of bibliographies as a means to this end. Like Conrad Gesner's _Bibliotheca universalis_ of 1545-1555 (which was a list of all writers and their works), Philip Labbé's _Bibliotheca bibliothecarum_ of 1653 (which was a bibliography of bibliographies) enjoyed a successful career for a little more than a generation and then disappeared from view. After the first revisions and supplements no one chose to continue either Gesner or Labbé. This analogy between the century that began with the invention of printing and ended with Gesner's survey of 1545-1555 and the following century that ended with Labbé's survey of 1653 is perhaps more curious than important. It does nevertheless emphasize a twice-repeated interruption in the historical development of bibliographies. In the two generations between 1643 and 1705 men in various countries compiled or promised to compile bibliographies of bibliographies and with the beginning of the eighteenth century they ceased to do so. The first separately published bibliography of bibliographies is, if it actually exists, Jodocus a Dudinck, _Bibliothecariographia_ (Cologne, apud Jodocum Kalcoven, 1643.) No one has ever seen it and many have searched for it during the last three centuries. Back in the seventeenth century the Lutheran theologian Caspar Sagittarius (1643-1694) sought it in vain. A little later Johann Andreas Schmidt or Schmid (1652-1726), who was both a theologian and a writer on library science, was similarly defeated in an effort to find the book. Probably Hieronymus Augustinus Groschufius was right when he said in one of the earliest treatises on rare books (1709-1716) that the _Bibliothecariographia_ was never printed.[57] The first reference to the book is found, as far as I know, in a Belgian biobibliographical dictionary of 1643 and all our information about the book and its author goes back to this source.[58] The announcement is not particularly suspicious because the publisher Jodocus Kalcoven of Cologne seems to have been an agent or a limited partner of the famous firm of Willem Blaeu (later Jan Blaeu) of Amsterdam.[59] This firm used Kalcoven's name on various scholarly books.[59] Little as we know about Dudinck's book, its title indicates that he clearly understood the nature of a bibliography of bibliographies. He called it "A Bibliography of Bibliographies. A list of all authors and works that have appeared under the title of bibliography, catalogue, index, list, athenae, and so