Jung discovered a striking correspondence between the symbols of the imagery of the unconscious and the symbols of alchemy. It becomes evident that the alchemical projections were merely a special case of general thinking, and that the individuation of the individual resembled the path that alchemists followed in their own way during their time. Although the processes in alchemy and individuation differ greatly, both represent attempts to lead humanity towards self-realization. This discovery is one of the cornerstones of C. G. Jung's work. Jung not only brought hidden aspects of alchemical science to light but also uncovered the historical counterpart to the psychology of the unconscious. Since 1928, he engaged intensively with alchemical texts and the deciphering of their symbols. Since then, his goal has been to fully demonstrate how my psychology corresponds to alchemy—or vice versa. Jung's discovery was tied to his interpretation of alchemical texts, to which he restored their mystical-psychological content. It was only the realization that the alchemist symbolically represents the transformation of the psyche through the chemical process that made alchemy for him an instrument for deciphering the unconscious. The texts presented in this volume are testimonies of this endeavor. In addition to the essay "Commentary on 'The Secret of the Golden Flower'," it exclusively contains works on alchemical texts: The Visions of Zosimos, Paracelsus as a Spiritual Phenomenon, The Spirit of Mercury, The Philosophical Tree.