The friend who had introduced me to Don Juan explained later that the old man was not a native of Arizona, where we met, but was a Yaqui Indian from Sonora, Mexico.

At first I saw Don Juan simply as a rather peculiar man who knew a great deal about peyote and who spoke Spanish remarkably well. But the people with whom he lived believed that he had some sort of 'secret knowledge', that he was a 'brujo'. The Spanish word brujo means, in English, medicine man, curer, witch, sorcerer. It connotes essentially a person who has extraordinary, and usually evil, powers.

I had known Don Juan for a whole year before he took me into his confidence. One day he explained that he possessed a certain knowledge that he had learned from a teacher, a 'benefactor' as he called him, who had directed him in a kind of apprenticeship. Don Juan had, in turn, chosen me to serve as his apprentice, but he warned me that I would have to make a very deep commitment and that the training was long and arduous.

In describing his teacher, Don Juan used the word 'diablero\ Later I learned that diablero is a term used only by the Sonoran Indians. It refers to an evil person who practises black sorcery and is capable of transforming himself into an animal — a bird, a dog, a coyote, or any other creature. On one of my visits to Sonora I had a peculiar experience that illustrated the Indians' feeling about diableros. I was driving at night in the company of two Indian friends when I saw an animal that seemed to be a dog crossing the highway. One of my companions said it was not a dog, but a huge coyote. I slowed down and pulled to the side of the road to get good look at the animal. It stayed within range of the headlights a few seconds longer and then ran into the chaparral. It was unmistakably a coyote, but it was twice the ordinary size. Talking excitedly, my friends agreed that it was a very unusual animal, and one of them suggested that it might be a diablero. I decided to use an account of the experience to question the Indians of that aria about their beliefs in the existence of diableros. I talked with many people, telling them the story asking them questions. The three conversations that follow indicate what they felt.