The Music of the Spheres — the Pythagorean-Platonic doctrine that the celestial bodies produce, through their proportioned motions, an inaudible or transcendent harmony — enters the depth-psychology corpus not as mere astronomical antiquarianism but as a living psychological metaphor for the ordered soul. Thomas Moore, drawing on Marsilio Ficino and Boethius, provides the most sustained treatment, distinguishing musica mundana (cosmic music), musica humana (the music of the soul), and musica instrumentalis (audible sound), arguing that modernity’s reduction of music to the third category represents a catastrophic loss of psychological depth. For Moore, the Pythagorean harmonia of the planetary scale serves as a template for the well-tempered psyche: distinct tones held in productive tension rather than collapsed into uniformity. Campbell situates the concept within the Hellenistic cosmological inheritance, tracing it from Scipio’s Dream through Dante, and reads Schopenhauer’s identification of music with the world-will as its modern philosophical recovery. Jung invokes the spheres’ harmony to anchor the sun-god Apollo’s lyre within the archetype of luminous order. Hillman discovers a Saturnine variant — an interior, barely audible music belonging to the hidden earth. Plato’s Timaeus provides the philosophical ground: number, musical ratio, and the motions of stars share a single mystery. The central tension in the corpus runs between cosmological literalism and psychological appropriation: does the harmony describe an objective celestial fact, a symbolic structure of the psyche, or both simultaneously?