There are few operatic works so cheerfully indifferent to morals as Così fan tutte, and it was largely deplored and rarely performed through most of the nineteenth century. Mozart’s librettist, Lorenzo Da Ponte, Jewish by birth, became a Catholic priest and then caused scandal by his libertine love affairs before leaving the priesthood; he was having an affair with the soprano who created the role of Fiordiligi. As for Mozart, he was the man who knew all about the serial courtship of sisters, since he first fell in love with Aloysia Weber and then married her younger sister Constanze.