The sketch-leaf is a solo by Bess at the final part of Act One, Scene Two, which eventually turns into a company number.
Shortly after Serena's husband, Robbins, is murdered by Bess' ex-lover, Crown, Bess finds herself in Catfish Row. She urges the residents to travel to the Promise Land, singing, "Oh the train is at the station an' you better get on board."
The manuscript is four pages long and is one of the most substantive known to exist from the opera.
Porgy and Bess is written by George and Ira Gerswhin along with original novelist DuBose Heyward. Notable recent productions include a Broadway adaptation starring Audra McDonald and Norm Lewis in 2012 and the English National Opera’s staging last year, which will cross the pond to open the Metropolitan Opera's 2019–2020 season this fall.
The auction will continue through June 21, with the manuscript estimated to sell for $25,000–$35,000. For more information, visit Sothebys.com.