In French opera (Manon, Hoffmann, etc.) we know that there are 2 "requirements" for a traditional production -- a ballet scene and a fairy tale scene.
I can understand the dance segment -- many traditional operas have a dance sequence. But what I can't understand is the fairy tale sequence -- for example, in Tales of Hoffman, we get the story of Kleinsach.
Does anyone know the origin of this tradition and why it persisted throughout French opera?