I have a theory about what caused her vocal decline, but it's more from watching her sing than from listening. I really think it was her weight loss that was so dramatic and so quick. It's not the weight loss "per se"—you know, Deborah Voigt has lost a lot of weight and still sounds glorious. But if one uses the weight for support, and then it's suddenly gone and one doesn't develop another musculature for support, it can be very hard on the voice. And you can't estimate the toll that emotional turmoil will take as well. I was told, by somebody who knew her well, that the way Callas held her arms to her solar plexus her to push and create some kind of support. If she were a Soubrette, it would never have been an issue. But she was singing the most difficult repertoire, the stuff that requires the most stamina, the most strength.