What is the theme in The Curing Woman by Alejandro Morales?

"The Curing Woman" is about the power of a great traditional healer to cure physical illness by working on the spiritual level. The work of Doña Marcelina rests on a dualistic theory of the universe in which there are good and evil powers. There is also a fluid interchange between spiritual and physical worlds. What this means in practice is that a person's illness may have causes other than merely physical ones. Since natural and supernatural worlds interact, evil spirits can take over a person's body and cause illness. But a skilled healer who understands how the cosmic forces operate can overcome these evil spirits.