In 1850, an epidemic swept America—but instead of leaving victims sick with fever or flu, this epidemic involved a rabid craze for the music of Swedish soprano Jenny Lind. American showman P. T. Barnum (who would later go on to found the circus now known as Ringling Bros. and Barnum & Bailey), a shrewd marketer and self-made millionaire, is credited with spreading “Lindomania” through a s…