Karoline von Günderrode was the oldest child of a Frankfurt patrician family. It was after she entered the Cronstetten-Hynspergische Damenstift (on the Frankfurt Roßmarkt) that she had a lively correspondence with her younger sisters. Here it is worth highlighting the close relationship between Günderrode and her sister Charlotte (1783–1801). In her letters, Günderrode emphasises the close connection she felt with Charlotte, that their souls were in sympathy with one another – an idea based on conceptions of friendship and love in both sensibility and Romanticism. Günderrode writes on this topic to her friend Karoline von Barkhaus on 20th December 1799: “Being with my sisters brings me a lot of joy, but every day I notice more and more that I am in the greatest harmony with her; never have I found a soul who is of the same view as me on the most important matters.” The closeness of the friendship between the two sisters is also demonstrated by the fact that the only extant portrait of Günderrode is attributed to Charlotte. The letters presented here are proof of their “lovely harmony”. At the same time, the letter itself is a topic of discussion – in particular, the extent to which it is possible to give expression to one’s feelings in writing.