I enjoyed Strassman's book. Another good writer is the anthropologist/ethnobotanist Wade Davis. Books that come to mind are, "One River" and "The Lost Amazon." "Into The Silence" and "The Wayfinders" are also excellent reads.
“All of these cultures are fundamentally driven by this idea that they, themselves, are the stewards of the forest- that plants and animals are just people in another dimension of reality, that there’s a transactional relationship between human beings and the natural world so that the hunter is both hunted and the hunter; where you don’t simply go to get meat, you must seek permission to get that meat; where the shaman is less a healer than a nuclear engineer who periodically goes to the very heart of the reactor to reprogram the world.”
“This sort of quest for individual health and healing, for individual enlightenment, individual growth- which, at some level, is completely understandable, but it is also a reflection, in good measure, of our own culture of self- the ongoing center of narcissism, the idea that one’s purpose in life is to advance one’s own spiritual path or one’s own destiny… that is, in my experience, very much not what is going on in the traditional reaches of the northwest Amazon, where the plant (the medicine) both originated, but also, where today, it’s taken very much as a collective experience, such that the ritual itself becomes a prayer for the continuity and the wellbeing of the people themselves- where you’d never even think of this in terms of self
"I think in general I agree with what Ram Dass [Harvard psychologist and psychedelics pioneer Richard Alpert] said: When you get the message, hang up the phone. How much do you have to do psychedelics to get the message? A lot of people think that if you take ayahuasca regularly, it’s going to somehow transform the processing of your life: similarly to a Buddhist practice, in which the idea is that the practice is a goal in itself. But [as to the idea that] you take [ayahuasca] repeatedly and it transforms you: I don’t see how taking ayahuasca repeatedly, every week, is going to achieve the illumination in the end that Buddhist practice would. What do you learn from the tenth trip you didn’t learn from the first one?"
Try pdfdrive.com for the book downloads and calibre is a good epub reader.