Western scientists and entheogen enthusiasts have used terms such as “psychoactive,” “hallucinogenic,” “psychedelic,” or more recently, “entheogenic,” to refer to shamanic plants and substances. Yet in all their permutations, such terms reinforce the foundational Cartesian dichotomy between body and mind, substance and spirit, the finite and the infinite. Indigenous peoples of the Amazon, by contrast, do not distinguish the mental or spiritual effects of shamanic plants and substances from their physiological or sensory properties. Among the Matsigenka people of Peru, for example, the term kepigari (which could be translated as “toxic,” or “intoxicating”) encompasses the physiological, sensory and cognitive dimensions of shamanic experience under a single, unified concept. The Matsigenka and other Amazonian peoples make no distinction between a shamanic plant’s active pharmacological ingredients and what we might refer to as the anthropomorphized “soul” that animates and infuses it with agency. Indeed, for the Matsigenka and other Amazonian peoples, the body can sometimes be used as a synonym for what we would refer to as the soul, and vice versa. And yet just as ethnobotanists might overlook the philosophical ramifications of indigenous ways of knowing, anthropologists in Amazonia, increasingly concerned with ontological questions, often overlook the material and phenomenological basis of indigenous knowledge. Indigenous concepts surrounding the sensory properties, body/mind manifestations and spiritual properties of shamanic plants transcend Cartesian dualism. Specific plants and plant-based substances are sometimes personified by Amazonian shamans as “plant teachers.” Scientific findings about the role of messenger molecules in plant communication and an emerging appreciation of “plant intelligence” provide new windows of understanding into the deep truth behind shamanic concepts.