Sulphur occupies a distinguished and irreducible position within the depth-psychological reading of alchemy. In Jung’s Mysterium Coniunctionis — the locus classicus for this term in the corpus — sulphur emerges as one of the two primary archetypal substances alongside Mercurius, and the intimacy between them is so profound that the tradition itself could scarcely tell them apart. Jung identifies sulphur as the soul of metals and of all living things, the ‘motive factor in consciousness,’ embodying desirousness, will, and compulsion — the fiery affect principle latent in the ego. Abraham’s lexicographical treatment traces sulphur’s role in the Geberian sulphur-mercury theory as the active, formal, masculine principle opposed to argent vive’s passive, material, feminine one. Edinger, interpreting Jung for clinical audiences, stresses sulphur’s dual nature: its corruptive, poisoning, infernal aspect and its capacity, when freed from its imprisoning complexes, to become a manifestation of the Self. Hillman, characteristically oblique, approaches sulphur through colour and its vivifying power — hudor theion, Holy Water — insisting that its significance must be read within alchemical process rather than reduced to symbolic abstraction. The key tension in the corpus runs between sulphur as destructive-demonic force (the dragon, Babel, concupiscence) and as the indispensable soul-substance whose liberation is the very aim of the opus.