"Attention American history buffs, here's a name you might not have heard before: Robert Ingersoll. According to author Susan Jacoby, he was 'one of the most famous people in America in the last quarter of the 19th century.'"

"'He went around the country,' Jacoby tells NPR's Rachel Martin. 'He spoke to more people than presidents. He was also an active mover and shaker behind the scenes of the Republican Party.'"

"But Ingersoll is largely forgotten today. His crime? Speaking out in favor of the separation of church and state. Jacoby, the author of a new biography The Great Agnostic: Robert Ingersoll and American Freethought, says he promoted Darwin's theory of evolution and fought publicly against government interference in religion."