The writer Arthur Schnitzler is one of the best-known characters of Viennese Modernism, sharing many similarities with Sigmund Freud in terms of both their work and their lives. Yet it was not until decades later that they met in person for the first time: a 'fear of one's doppelgänger', as Freud wrote to Schnitzler on May 15th 1922, had prevented him from seeking a face-to-face conversation with the other man.

In the above letter, dated June 8th 1922, Freud invites Schnitzler to 'join us for an evening meal? We are: my / wife and my daughter, whom you already know, / apart from myself. No one else / will be present.'

In his diary, Schnitzler writes of this encounter: 'He was very cordial. We talked about our time in hospital and in the military, our shared superiors, etc. ... – He accompanied me late at night from Berggasse to my flat. – The conversation became warmer and more personal; – we spoke of ageing and dying.' The letter is representative of the valuable collection of original documents held by the Sigmund Freud Museum, written by Sigmund Freud and his closest circle.

Margarethe Trautenegg (1900–1999), née Csonka, was sent to Dr Freud by her parents because of her homosexual inclinations. As the patient was not suffering from any inner conflict or illness, and did not otherwise develop any personal motivation to undergo analysis, Freud soon discontinued the treatment. Nevertheless, she provided the inspiration for a paper: 'On the Psychogenesis of a Case of Female Homosexuality' (1920).

Under the Nazi regime, Csonka-Trautenegg emigrated to Cuba, where she rediscovered her former hobby of portrait painting, but returned to Vienna via Paris in 1949. In the decades that followed, she also worked as a language teacher and governess. She spent her later years travelling frequently until she died in Vienna in 1999, aged almost one hundred.

The Sigmund Freud Museum holds a partial collection of Csonka-Trautenegg's estate, comprising numerous photographs, photo albums, documents and letters from her life. The collection also includes research material relating to the biography 'Heimliches Begehren. Die Geschichte der Sidonie C.' by Diana Voigt and Ines Rieder.

At the time of Sigmund Freud's flight to London in June 1938, four of his five sisters were still living in Vienna. All attempts to bring Adolfine Freud (1862–1942), Maria Freud (1861–1942), Rosa Graf (1860–1942) and Pauline Winternitz (1864–1942) to join him in exile failed due to the impossibility of obtaining exit permits or entry visas for them. All four were deported to Nazi extermination camps and murdered there.

The collection at the Sigmund Freud Museum comprises a wide variety of documents relating to financial and legal proceedings as well as handwritten letters from the sisters to various individuals, solicitors and notaries in their efforts to settle their financial affairs in accordance with the regime's regulations and to obtain the necessary documents for departure. The written records reveal the difficult conditions under which the four elderly ladies were forced to live. The collection served as one of the main sources for the temporary exhibition 'The Freud Case: Documents of Injustice'.