Pietro Antonio Cesti’s 1657 dramma musicale La Dori is a hoot. It seems to prefigure every plot device that will ever be used in opera. A baby sold by bandits who turns out to be a princess. Pirates. A ghost. Mistaken identities. Swapped potions. Men pretending to be women. Women pretending to be men. Love polygons of fiendish complexity. I won’t even attempt to explain the plot because it’s very complex and silly and hardly matters. It took me a half page diagram just to map the relationships between the characters.