The article consists in a general study of the people of Mexico regarding the ways of establishing the origins and basic causes of illnesses. The author finds four basic causes of illnesses that can be related to each other: natural, social, divine and seasonal. The different methods of diagnosis, pulse, corn-reading and divinatory dreams, show the essential features of the specialists, their powers and their relation to the natural and spiritual world. The diagnosis methods have within themselves healing powers where physical illnesses cannot be separated from the spiritual.