In the book Castaneda continues his description of his apprenticeship under the tutelage of Don Juan. As in his previous book, The Teachings of Don Juan: A Yaqui Way of Knowledge, Castaneda describes the experiences he has with Don Juan while under the influence of the psychotropic plants that Don Juan offered him, peyote (Lophophora williamsii) and a smokable mixture of what Castaneda believed to be, among other plants, dried mushroom of the genus Psilocybe.