he teacher and student sit cross-legged, facing each other on the floor of the open-sided hut in Western Samoa. Behind them the rain forest rises to the pinnacle of a long-dormant volcano. Beneath the thatched roof, a gaggle of children intently watches the proceedings. The teacher is Salome Isofea, 30, a young healer who is demonstrating her art. The man opposite her, a Westerner named Paul Alan Cox, is no ordinary student. He is a botany professor and dean at Brigham Young University in Provo, Utah, a world specialist in medicinal plants and, far from least in this exotic setting, the paramount chief of the nearby village of Falealupo. To people here, he is known as Nafanua, in honor of a legendary Samoan warrior goddess who once saved the village from oppression and protected its forests.

Salome is explaining a traditional cure for pterygium, an eye affliction common to the tropics in which vision gradually becomes obscured as a layer of tissue encroaches over the cornea. The traditional cure used by healers is leaves of Centella asiatica, a ground-hugging vine, which Salome chews into a poultice, smears on a cloth and then places as a compress on the afflicted eye for three consecutive nights.

But before this can be done, Salome explains, there is another crucial part of the cure. Holding a coconut-shell bowl containing ashes, she flicks them in the direction of Cox, who is playing the patient. When he soberly asks why the ashes are necessary, she replies that they enhance "spiritual transmission" between healer and patient. "We Westerners have to suspend judgment at these times," says Cox. "Look at our own belief in doctors wearing white coats. In Western culture that uniform is comparable to the 'spiritual transmission' she sees in the use of ash."