According to an old proverb, which reminds us that substances have both the potential to heal or destroy depending on how we use them, “the dose makes the poison.” To many indigenous people of the Amazon, plants are often seen to hold the truth of nature’s wonders; therefore, tobacco is highly regarded for its role in traditional medicine and spiritual awakening—a stark departure from how it’s used (and negatively viewed) by Western cultures. Likewise, ayahuasca is used by indigenous people to heal the body, stimulate the mind, and act as a spiritual guide. In Plant Teachers, anthropologist Jeremy Narby and traditional-healer Rafael Chanchari Pizuri discuss the cross-cultural connections between ayahuasca and tobacco, exploring the similarities and the perceived controversies, while raising tantalizing questions about the relationship between science and other ways of knowing.