ROBERT SIEGEL, HOST:
Twenty-nine bars of music are making classical fans giddy today. Those bars make up a song called "The Heart of Man is Like a Mine."
AMY WILLIAMSON: (Singing in foreign language)
SIEGEL: It was written by composer Felix Mendelssohn.
MELISSA BLOCK, HOST:
Mendelssohn wrote the song in 1842, when he was 33 years old. It was a commission for an acquaintance.
ANASTASIA TSIOULCAS, BYLINE: He'd had no intention of publishing this or making it go public in any way.
BLOCK: That's Anastasia Tsioulcas with NPR Music. She says the song was performed privately and the manuscript was sold at auction twice, the last time in 1872.
TSIOULCAS: And then after that, it vanished. So scholars knew about it and some musicians knew about it but they assumed that the manuscript was lost.
SIEGEL: And now that original manuscript has been rediscovered.
WILLIAMSON: (Singing in foreign language)
SIEGEL: So where has this manuscript been for more than a century? Well, Tsioulcas only knew it was found somewhere in the U.S. among papers belonging to the current owner's grandfather, a musician and a Mendelssohn fan.
BLOCK: Christie's will put the original manuscript on the auction block later this month. The single page of music, which includes Mendelssohn's signature, is expected to sell for up to $42,000.
TSIOULCAS: So we're not sure why it's come to market now or why the family has decided to sell right now. But it's an enchanting discovery nonetheless.
WILLIAMSON: (Singing in foreign language)
SIEGEL: By the way, the version that we've been hearing was performed today on BBC Radio. That's alto Amy Williamson and pianist Christopher Glynn.
BLOCK: And you can hear the complete song - only a minute and a half long - at NPR.org.
WILLIAMSON: (Singing in foreign language) Transcript provided by NPR, Copyright NPR.