Etty Hillesum and Julius Spier communicated in various ways: they met in person, exchanged phone calls, and wrote letters. Hillesum copied several of these letters, or fragments thereof, in her diary notes, the first being a well-known text: it acts as the preface to her first notebook. This and many other letters, including the (fragments of) 71 in the section “Letters from Etty Hillesum,” have become part of Etty: De nagelaten geschriften van Etty Hillesum, 1941-1943 (1986) [E.T.: Etty: The Letters and Diaries of Etty Hillesum 1941-1943 (2002)]. However, a few texts were not included in the complete edition of Hillesum's literary legacy. Together with some other documents, they had been stored in a binder and were forgotten by the time the complete edition of Hillesum's writings in Dutch was published in 1986. In December 2012, however, Jan Geurt Gaarlandt, the Dutch publisher of Hillesum's work, opened the binder and discovered the texts anew.

One of the findings in the tucked away folder was the copy of a letter Hillesum wrote to Spier on 17 March 1942. Since the text, on a sheet of thin paper, is typed, it cannot be recognized through Hillesum's characteristic handwriting. Also, it lacks an addressee and signature. Yet, set in the German language, with a date and several sentences identical to sentences in Hillesum's fifth notebook, there is enough evidence to prove that she was the author.