 Works with libretti by Michel-Jean Sedaine were particularly influential.The influx of suspenseful or tragic subjects into "opéra comique" caused confusion in a system where tragedy was associated with through-composed scores and comedy with dialogue, precipitating a shift of musical theatre genres that paralleled the political shift which empowered the middle-class.Carl Dahlhaus writes, "No longer did the bourgeoisie function in comic casts merely as the butt of jokes; it demanded, and received, its part in the dignity of tragedy."