In the days before the term “contemporary music” came to bear a tinge of the pejorative, the greatest composers wrote music for the greatest artists, and opera was not sacred but alive. Adelina Patti, after a certain number of curtain calls in Verdi’s La Traviata, would drag a piano out on the set and sing her signature piece, “Home Sweet Home,” as an encore. (One of her at-home recordings is shown.)