Judy Garland sang the poplular song, I’m Always Chasing Rainbows. Harry Carroll is credited with writing it, but the plaintive melody for this tune was lifted from the center of Chopin’s Fantasie-Impromptu in C-sharp minor.
It turns out playing the outer segments of Chopin’s work is a rainbow-chase all its own. Lyricist Joseph McCarthy likely didn’t know when in 1917 he wrote the word "My life is a race, just a wild goose chase" that he was pointing at exactly what it takes to sing the song in the faster portions of Chopin’s piece.
In his bestseller, This is Your Brain on Music: The Science of a Human Obsession Daniel Levitin observes, In Chopin’s Fantasie-Impromptu, "The notes go by so quickly that an illusory melody emerges." Levitin explains, "Due to stream segregation, the melody 'pops out' when the notes are close enough together in time — the perceptual system holds the notes together — but the melody is lost when the notes are too far apart in time."
Like the rainbow in McCarthy’s lyrics, it takes just the right atmospheric conditions to produce beauty — and song — out of thin air. - Jennifer Foster