This book investigates the cognitive and phenomenological structures of the altered states of consciousness induced by the Amazonian brew Ayahuasca. Benny Shanon, a cognitive psychologist, utilizes a rigorous empirical framework to categorize the subjective experiences reported by users of the substance. By synthesizing personal accounts with extensive interviews of indigenous shamans and diverse practitioners, the author constructs a theoretical model for understanding non-ordinary states of mind. The work bridges the gap between subjective experience and objective psychological analysis, providing a structured taxonomy of the visions and cognitive shifts associated with the brew.

Experts and researchers in the field of consciousness studies recognize this work as a foundational text for its systematic approach to a traditionally subjective topic. Readers frequently note the academic density of the prose, which balances rigorous psychological theory with detailed ethnographic observation.