For the Enlightenment mind, from Moses Mendelssohn's focus on the moment of surprise at the heart of the work of art to Herder's imagining of the seismic moment at which language was discovered, it is the flash of recognition that nails the essence of the work, the blink of an eye in which one's world changes.

In Cherubino's Leap, Richard Kramer unmasks such prismatic moments in iconic music from the Enlightenment, from the "chromatic" moment--the single tone that disturbs the thrust of a diatonic musical discourse--and its deployment in seminal instrumental works by Emanuel...