The admired pianist, wife of composer Robert Schumann, and close friend of Johannes Brahms and Joseph Joachim, writes a letter on both sides of her visiting card: Dear Friend, The ladies who are bringing you this card I’d like to introduce to you as my sister Cacilie Bargiel with her very dear friend Laura Peters; both of them have the desire to permanently settle in Baden and I would be heartfully thankful if you would receive them in a friendly manner. I was unable to say goodbye to them, because I received news which forced me to depart earlier than planned. With the warmest greetings…

Cäcilie Bargiel (1832–1910) was Clara's half-sister. Their mother, Mariane, remarried Adolph Bargiel, a piano and voice teacher, after her contentious divorce from Clara's father, Friedrich Wieck. Together Mariane and Adolph had four children, of whom Cäcilie was the third.

Clara and Cäcilie seem to have enjoyed a closeness despite their thirteen-year age gap. In one extant letter Clara reports having spent two weeks with her sister over a summer holiday. And in a diary entry of 1895, evidently following a visit from Cäcilie and Laura, Clara regretted that she would miss them very much. Cäcilie was always so charming to me, so attentive, even though she herself was in need of care. Whether we would ever seen each other again was what I thought as I said goodbye, and my heart was filled with sadness.