Nachlass (German pronunciation: [ˈnaːχlas], older spelling Nachlaß) is a German word, used in academia to describe the collection of manuscripts, notes, correspondence, and so on left behind when a scholar dies. The word is a compound in German: nach means "after", and the verb lassen means "to leave". The plural can be either Nachlasse or (with Umlaut) Nachlässe. The word is not commonly used in English; and when it is, it is often italicized or printed in capitalized form to indicate its foreign provenance.
The Nachlass of an important scholar is often placed in a research library or scholarly archive. Other workers in the scholar's area of specialization may obtain permission to comb through the Nachlass, seeking important unpublished scholarly contributions or biographical material. The content of a Nachlass can be catalogued, edited, and in some cases published in book form.
Such publication is more difficult for a Nachlass that contains a great deal of material, such as that of Gottfried Leibniz. In such cases, it may not be financially possible to publish its entire contents. The Nachlass of Ludwig Wittgenstein, kept at the University of Bergen, has been digitized and published in compact disc format.
Klagge and Nordmann note a conflict that faces an editor choosing what to publish draft material from a Nachlass: to understand a scholar (in this case Wittgenstein) "as he would want to be understood, we should focus on the works that came closest to passing muster with him." Yet publication of draft material may perhaps assist in a deeper understanding of the published versions, and also help understand the process whereby the scholar created his or her works.
Sometimes it is known what the original scholar's view was concerning what should be done with his or her Nachlass, and these views differ greatly. Near the end of his life Gottlob Frege wrote to his adopted son: