May 3 is the date of the 140th running of the Kentucky Derby. Since the 1930s, the occasion has been marked by a stirring ritual: before the horses break from their gates, more than 100,000 spectators rise from their seats at Churchill Downs for the singing of "My Old Kentucky Home" — a 19th century minstrel song by Stephen Foster.

What do those spectators, along with the race's millions of TV viewers, think they're singing?

Mostly likely, the song comes across as a nostalgic ode to a more genteel time in the life of the South. But that's not the song that Foster wrote in 1854. Inspired by the novel Uncle Tom's Cabin, he instead penned a lament by a slave in Kentucky who's been sold down the river to the Deep South by his master. The slave is both saying goodbye to his old Kentucky home and preparing to meet his imminent death from overwork and brutal mistreatment in the "land where the sugar canes grow."

The problem is that Foster told the story by using words that are offensive to modern ears. In 1986, The Kentucky General Assembly passed a law that removed the words "darky" and "darkies" from the song and replaced them with "people." The same law requires that the new lyrics be sung at official state functions.

Ken Emerson, author of a biography on Foster, describes the effect on the scene at Churchill Downs: "I find it very ironic that all these men and women in their lovely hats and fancy gowns are singing a song with adulterated lyrics and they think they are singing a song that is a celebration of the Antebellum South, with ladies in crinoline and dashing cavaliers."

Foster began his career in the 1840s writing songs in the minstrel style. He had several big hits, including "Oh Susannah," "Camptown Races" and "The Old Folks at Home." It's a fact that, early in his career, he wrote a number of ugly songs. But his attitudes changed over time, and his musical portrayals of African Americans gained in dignity.

He was a songwriter of undisputed brilliance who is often called the father of American music. But he died he broke and alone in New York City.