English: Karl Benedikt Hase (1780–1864) is recognised as one of the foremost Greek scholars in the French academia of his time. Recently nine volumes of the private diary of Hase, written in Ancient Greek and preserved at the Goethe- und Schiller-Archiv, Weimar, has been found. Specialists of Late Antique and Byzantine history and literature applaud the outstanding value of his work as an editor and commentator. They have also, however, identified him as the perpetrator of a series of forgeries on documents of Byzantine history.