The Mapuche Philosophy lies in the balance between the forces of nature and spirit. They have to maintain equilibrium between positive and negative forces to heal sick person. For example, pain, happiness, resentment or hatred often could be the root cause of diseases. The use of medicinal herbs is combined with some common ways of diagnosis such as looking at the urine or the clothes of the sick person.
There are two types of medicinal herbs. One is used for healing and the other one is used for revealing disease. The last one allow machi to contact with the spirit world or ngenmapu. Laurel tree, Canelo tree and wilel lawen (herb of the fortune teller) are plants that allow the contact: foye (canelo tree) talks with kila and thus each one is put in contact with another natural element.
The power of the herbs
Machis and huimpife know hundreds of herbs for medicinal use. One of the tree that have played the most important roles in Mapuche ceremonies is Foye (canelo tree) which is the sacred tree of The Mapuche people.
Canelo tree or foye (Drimys winteri).
Other important plants are cachenlahuen, viravira, retamilla, paico and quinchamalí. The medicinal plants play a central role in sacred rituals or ceremonies such as ngill.
The machi knows the properties of the medicinal plants, because of that the relation between collective and ancestral knowledge is more complex and deep.
Source : http://www.conama.cl/certificacion/1142/articles-29101_recurso_2.pdf.