With the exception of Robert and Clara Schumann, no relationship between two European musicians of different genders is as famous as that of Fanny Hensel and Felix Mendelssohn Bartholdy, siblings who have always been linked in biographical depictions. Many of Felix's first published letters, appearing in the two decades after his death, were to Fanny, and the memoirs of friends such as Ferdinand Hiller, Eduard Devrient, and Ignaz Moscheles, who knew him from childhood, all mention his talented sister. Awareness of Fanny's musical abilities spread well outside the family circle during her lifetime; as early as 1830, John Thomson, writing in The Harmonicon, declared that Fanny composed “with the freedom of a master.” After her death, but even before the family history by her son, Sebastian Hensel, was published in 1879, recognition of “Mendelssohn's sister” began to appear in wide-ranging sources. The biographical dictionaries of Carl von Ledebur and François Joseph Fétis, both from the 1860s, contained entries on Fanny. In his 1869 inventory, Hereditary Genius, British scientist Francis Galton listed both Mendelssohn and his “very musical” sister, described as “of high genius.”