The private library of both the philologian Tiberius Hemsterhuis (1685-1766) and his son, the philosopher Frans (Franciscus, François) Hemsterhuis (1721-1790), was sold by auction in 1791. The auction catalogue has been preserved and it offers a treasure of information about the sources available to these two eminent scholars. This catalogue will be reprinted photomechanically, with an introduction, additional appendices and indexes. The reprint will be made from the copy of the auction catalogue preserved in the Public Office in The Hague, with the prices handwritten in the margin. Furthermore, the new edition includes a bibliography of both of these scholars, and a genealogy, which shows how this Frisian family of farmers became a family of scholars during the 16th-18th centuries.