The Phantom of the Opera by Gaston Leroux:
But the real triumph was reserved for Christine Daaé, who had begun by singing a few passages from Romeo and Juliet. It was the first time that the young artist sang in this work of Gounod, which had not been transferred to the Opera and which was revived at the Opéra Comique after it had been produced at the old Theatre Lyrique by Mme. Carvalho. Those who heard her say that her voice, in these passages, was seraphic; but this was nothing to the superhuman notes that she gave forth in the prison scene and the final trip in Faust, which she sang in the place of La Carlotta, who was ill. No one had ever heard or seen anything like it.
Daaé revealed a new Margarita that night, a Margarita of a splendor, a radiance hitherto unsuspected. The whole house went mad, rising to its feet, shouting, cheering, clapping, while Christine sobbed and fainted in the arms of her fellow-singers and had to be carried to her dressing-room. A few subscribers, however, protested. Why had so great a treasure been kept from them all that time? Till then, Christine Daaé had played a good Siebel to Carlotta’s rather too splendidly material Margerita. And it had needed Carlotta’s incomprehensible and inexcusable absence from this gala night for the little Daaé, at a moment’s warning, to show all that she could do in a part of the program reserved for the Spanish diva! Well, what the subscribers wanted to know was, why had Debienne and Poligny applied to Daaé, when Carlotta was taken ill? Did they know of her hidden genius? And, if they knew of it, why had they kept it hidden? And why had she kept it hidden? Oddly enough, she was not known to have a professor of singing at that moment. She had often said she meant to practice alone for the future. The whole thing was a mystery.