One of the most significant printers of German-language heterodox, spiritualist, and hermetic works in the seventeenth-century United Provinces has long been its most enigmatic. Between late 1645 and early 1650, Hans Fabel (1616-after 1650) originally of Wetzlar, printed or published at least sixty-two books and pamphlets at his offices in Amsterdam. In sheer quantity, these works made him one of the most prolific printers of German-language books in the United Provinces during this short period. However, in the secondary literature on the European book trade, Fabel has been dismissed as a 'fictive imprint' or a virtual publisher. Drawing on a variety of heretofore unknown or overlooked sources, both manuscript and print, this article presents for the first time a detailed bio-bibliographical account of Fabel's Amsterdam enterprise. It situates his activity within a variety of different contexts, the most important of these being his participation in the overlapping correspondence networks product of the dislocations of the Thirty Years' War, particularly those of the London intelligencer Samuel Hartlib (ca. 1600-1662), and the Silesian mystic Abraham von Franckenberg (1587-1652). Indeed, the Thirty Years' War was crucial to the trajectory of Fabel's business. The printer's own youthful experiences of the conflict in Wetzlar probably engendered within him an inclination to specialize in printing spiritualist works which condemned religious squabbling and conflict; his networks provided his business with customers, copy, and investors, and, finally, the end of the conflict in 1648 appears, along with economic considerations, to have decisively influenced his decision to leave Amsterdam and return to his native Germany. This investigation is seen as a further contribution to charting the terra incognita of the heterodox and clandestine bookmarkets and cultures of central Europe during the seventeenth century.