Imagination, of course. But the important thing is that she was born full of color, with a rich personality. That's a gift of the gods, like a fine nose. You have it, or you haven't. Against it, intelligence and musicianship and habits of industry don't count at all.
Singers are a conventional race.
When Thea was studying in Berlin the other girls were mortally afraid of her. Fred thrust his hands into his pockets and leaned back against the piano. Landry shook his head. That's what constitutes real equipment. What she does is interesting because she does it.