In 1982, the German philosopher Helmuth Plessner donated his archive to the University of Groningen. The Special Collections Department of the University Library preserves the archive, which takes up more than 10 meters of bookshelves. Amongst other things, it consists of manuscripts of articles, lectures, letters, (research) reports and newspaper clippings.

The part of this archive which has been disclosed with Omeka S consists of the 13 000 letters which Plessner sent and received during his lifetime. The letters are both private and scientific in nature. The inventory of his letters reveals the wide-ranging network Plessner was part of: he corresponded with philosophers, academics, politicians, and many others. The archive takes an important place among the Special Collections at the University of Groningen Library.