This volume offers a new annotated translation, also with a new introduction, of the Dialogue on the True Medicine, one of a series of dialogues published in 1587 as Nueva Filosofia de la Naturaleza del Hombre (New Philosophy of Human Nature), under the name of Oliva Sabuco de Nantes Barrera. Believed for centuries to be a woman's work, the book was attributed to Oliva's father, Miguel Sabuco, in the early twentieth century, and its authorship remains a matter of controversy today. Sabuco's work is one of the most intriguing texts of sixteenth-century medicine. Defined by its author as "a book that was missing in the world," the work proposes a new ambitious medical theory challenging the humoral view of disease and the main tenets of Galenic physiology. This annotated translation allows the reader to locate the Dialogue on the True Medicine in the context of early modern medical and philosophical culture, identifying Sabuco's ancient and modern sources. The editor's introduction reviews the contested issue of authorship, offers new documentation for the history of the reception of Sabuco's ideas in the seventeenth century, and relates Sabuco's work to the Querelle des femmes, the protofeminist debate which had remarkable echoes in early modern medicine.