In 1970, a record collector located an original, long-lost sonata signed “F Mendelssohn” in a French bookstore. This collector immediately ascribed the masterpiece, “Easter Sonata,” to Felix Mendelssohn, a German composer born in 1809. The problem, as one scholar discovered decades later, was that it wasn’t Felix’s work after all. It was a composition by his older sister, Fanny Mendelssohn, a piece that has finally been performed under her name for the first time, as The Washington Post reports.

In 2010, Duke University grad student Angela Mace was able to examine the original manuscript, which was owned by a private collector and previously inaccessible to scholars. Looking at Fanny’s diary, letters and handwritten scores, Mace determined that the handwriting on “Easter Sonata” was hers. In addition to the fact that the title of the piece, “Ostersonate,” was written in Fanny’s hand, her diaries mentioned having composed the work, and the page numbers matched the missing numbers in another manuscript she authored.

Mendelssohn was not allowed by her family to pursue a musical career like her brother’s, but she was a prodigious talent, and composed “Easter Sonata” in her early 20s. It wasn't the only one of her works that her brother got credit for: Fanny let Felix publish six of her pieces under his name in his Opus 8 and Opus 9, though he wouldn’t give her his blessing to publish under her own name, according to Sheila Hayman, one of Fanny’s descendants. While she wrote around 500 compositions during her life, few were published before her early death at age 41.

In honor of International Women’s Day, “Easter Sonata” was performed for the first time under Fanny Mendelssohn’s name, played by the pianist Sofya Gulyak in London on March 8. Henri-Jacques Coudert, the record collector who first found the manuscript, still insists it was Felix’s.

[h/t The Washington Post]