In The Seventeenth-Century Orange-Nassau Library, the handwritten catalogue of the Orange-Nassau library, nowadays preserved in the Koninklijke Bibliotheek (Royal Library) at The Hague, is published complete and unabridged. This catalogue was compiled by the librarian Anthonie Smets under the supervision of Constantijn Huygens in 1686. Starting with John IV of Nassau (1410-1475), the library described was collected and inherited by successive generations of Counts of Nassau and Princes of Orange, and eventually became the property of William III, the King-Stadholder (1650-1702). When William III died without issue, a prolonged inheritance dispute ensued, at the end of which the library was allocated to the King of Prussia. He eventually decided to auction the library at The Hague in 1749. At the auction, a small part of the former book collections of the Princes of Orange was bought by Stadholder William IV. Together with the library of his successor William V, these acquisitions became the basis of the present Koninklijke Bibliotheek in 1798. The 1686 catalogue describes the holdings of the seventeenth-century Orange-Nassau library at the moment when it was virtually at its largest.

Besides the 1686 catalogue, all known contemporary lists and catalogues about the library (the earliest dating from 1608/1609, and the last from 1750) are published here, partly in full. Several until now unknown catalogues have been brought into connection with the library here for the first time. The administrative documents of the librarian, Anthonie Smets, nowadays also preserved in the Koninklijke Bibliotheek, have also been incorporated, complete and unabridged. After comprehensive bio- and bibliographical research the titles in these listings have been supplemented in so far as this was considered desirable and justifiable, and made accessible through several indexes and concordances. With these data the development and subsequent dispersion of the library can be reconstructed. Moreover, extensive investigations took place to trace the vicissitudes of the manuscripts and printed works in the library after the 1749 auction, and their present locations. As a result the provenance and present location of some hundreds of Orange-Nassau copies could be established.

In the extensive historical introduction the complete history of the library has been reconstructed in chronological order. Archival research in the Netherlands and abroad, notably in The Hague, Göttingen, Merseburg, Berlin, and Paris, yielded not only manifold additions and corrections, but also gave rise to new perceptions on the history of the library. Thus, in particular, data concerning the accommodation of the library in the seventeenth century, the Prussian inheritance procedure, the auction and subsequent dispersion of the library, the history of William IV’s acquisitions, and events during the French occupation of Holland could be significantly supplemented or put in a different light. Several superseded theories could be discarded.