In "The Toad and the Jaguar: A Field Report of Underground Research on a Visionary Medicine," Ralph Metzner embarks on an enlightening journey through the hidden realms of consciousness exploration, guided by the potent enigmatic substances Bufo alvarius and 5-methoxy-dimethyltryptamine. Drawing on over three decades of meticulous observation and personal experiences within clandestine circles in the United States and Europe, Metzner illuminates the shadowy path of psychedelic research that has operated beneath the radar of mainstream cultural and legal boundaries. This compelling monograph is not merely a collection of ethnographic anecdotes; it is a profound exploration of the mystical and transformative experiences facilitated by these substances, challenging the reader to reconsider the nature of consciousness itself. Metzner, a pioneering psychologist and esteemed scholar, delves into the spiritual and cosmic dimensions that emerge from the entheogenic use of these compounds, transcending the traditional confines of physical and psychological analyses. His narrative is enriched by the voices of participant-observers, whose testimonies add depth and color to this extraordinary exploration of the mind's farthest frontiers. "The Toad and the Jaguar" is more than a report; it is an invitation to journey through the uncharted territories of the psyche, offering insights into the profound interconnectedness of existence. With Metzner as our guide, we are led to question the very fabric of reality, opening doors to understanding that reach beyond the high walls of conventional prohibitions and into the vastness of human consciousness.