Swans sing until the end of their lives.

But Rossini stopped singing in the middle of his.

—Heinrich Heine

During the last decade of his life, Gioachino Rossini, the “Swan of Pesaro” and composer of some of the most popular operas of the nineteenth century, held regular Saturday evening receptions at his Paris apartment at 2 Chaussée d’Antin or, during the summer, at Beau Séjour, his house in Passy, then in the countryside outside the city.

Although this sort of salon was fairly typical (the well-connected could easily attend different salons almost every night of the week), within a few months of the Rossinis’ first samedi soir in December 1858, an invitation was the city’s highest social prize. Musicians, danseuses, critics, and authors...