Peter Gorman, an investigative journalist and long-time expert on Amazonian curanderismo, has an excellent piece today on ayahuasca and the plant spirits. Here is the money quote:
We are not discussing chemicals. Chemicals are zero in this equation. We're discussing the invitation of spirits who can have an important impact on our lives. The meditation and smoking of black tobacco during cooking is probably much more important than any chemical that can be extracted from the plants. Because that 8-10 hour meditation is what invites the spirit of the plants. The plants themselves are not worth much. Their spirits are worth a great deal. And if you are going to invite living beings, beings with intent, will and desires into your physical/ emotional/ spiritual/ soul space, then you'd better be sure you know who they are and how to treat them as guests.
This strikes me as being absolutely true. Read the whole thing.