This brief historical summary makes it plain that a bibliography is or, at least, it has become a reference work that gives a limited amount of information of a very special kind. It is immediately useful in an emergency and less likely to be helpful in surveying historically any particular field of study. A corollary is the fact that a bibliography of bibliographies will ordinarily give a student little or no new information about a subject with which he is familiar, but can be a valuable aid to him in an unfamiliar field. A student of Renaissance English literature will not consult a bibliography of bibliographies to learn of such works as the _Cambridge Bibliography of English Literature_ or A. W. Pollard and G. R. Redgrave, A _Short-Title Catalogue of Books Printed in England ... 1475-1640_. He already knows them. He may be very glad to find the titles of bibliographies of theology, history, or science that meet his needs. He should consult, also, the older books that Besterman alone among modern writers of the bibliography of bibliographies is likely to cite. Joris Vorstius rightly emphasizes the fact that a bibliography of bibliographies serves primarily a reference librarian.[212] I should only enlarge upon his remark by saying that the older bibliographies of bibliographies are invaluable and all too little known aids to understanding the historical development of a discipline or the background of an earlier period. With all their faults and insufficiencies--and what human works lack them?--bibliographies of bibliographies are very valuable aids to scholars. As an introduction to a strange field one will naturally consult only the most recently published examples, beginning with Julius Petzholdt, _Bibliotheca bibliographica_ (1866) or perhaps even with Theodore Besterman, _A World Bibliography of Bibliographies_ (2d ed., 1947-1949; 3d ed., 1955-). In studying the historical development of a discipline or subject one can neglect the four oldest bibliographies of bibliographies. Gesner's _Pandectae_, Spach's _Nomenclator_, and Bolduan's _Bibliotheca philosophica_ are general subject bibliographies of a sort that I hope to discuss at another time. These books and Sweert's _Athenae Belgicae_ contain little or nothing as far as bibliographies are concerned that cannot be more easily found in other books. With the sole exception of Labbé's _Bibliotheca bibliothecarum_, which was absorbed into Teissier's _Catalogus auctorum_, a student of the historical aspect of a subject must consult all the bibliographies of bibliographies printed after 1664. They are independent or almost independent compilations and supplement one another. Fortunately they are not extremely difficult to obtain. In consulting them the modern scholar should give thanks to those who have labored so diligently in his behalf. FOOTNOTE: