According to his official North Korean biography, Kim Jong Il initiated “an epochal change in the history of the modern opera” by introducing an offstage song called a pangchang—an innovation, claims the bio, “greater than the discovery of the heliocentric theory by Nicolaus Copernicus or the discovery of the New World by Christopher Columbus.”

In 2014 Amelia Hamrick, an undergraduate at Oklahoma Christian University, noticed musical notes written across the buttocks of one of the denizens of hell depicted in Hieronymus Bosch’s painting The Garden of Earthly Delights. She transcribed it into modern notation and made a recording she posted on her blog. “So yes,” she wrote, “this is literally the 600-year-old butt song from hell.” The post went viral.

In an 1899 treatise written while in exile, Vladimir Lenin critiqued the capitalist growth of Russian industries in which factory workers had replaced skilled craftsmen. Among his concerns was a shift toward the mass production of cheap accordions, which, he complained, “have nearly everywhere displaced the primitive string folk instrument, the balalaika.”

Irving Berlin composed most of his songs in F-sharp major; the six sharp notes in the scale meant he could play the black keys of the piano almost exclusively. Eventually, for purposes of technical variety, he had a lever mechanism installed that allowed him to modulate into other keys without changing his playing.