Salt — the alchemical sal — occupies a position of singular complexity within the depth-psychology corpus, functioning simultaneously as cosmological principle, psychological substance, and moral register. Its primary theorist in the modern tradition is James Hillman, whose extended treatment in Alchemical Psychology reconstructs sal as one of the tria prima (alongside sulfur and mercury), the principle of fixity, embodiment, and — crucially — the suffering that confers wisdom. Jung’s foundational exposition in Mysterium Coniunctionis establishes the dual valence that all subsequent commentators inherit: salt as amaritudo (bitterness, tears, sorrow) and as sal sapientiae (the salt of wisdom), coordinated with the feminine and with Luna. Edinger distills this duality into the clinical formula that bitterness and wisdom are alternatives carried by the same substance. Von Franz anchors the fairy-tale dimension, reading salt as the Eros principle — pungent, life-giving, isolating. Hillman presses furthest, insisting that salt is the archetypal ground of common human experience, the substrate without which events leave no psychic residue, and warning that its puristic fixation — salt unopened by sulfur or mercury — becomes fanatical and destructive. The critical tension running through every treatment is between salt as preservative and nourishing principle and salt as corrosive, self-enclosed, barren absolute: the difference, as Hillman puts it, between the soluble and the crystallized.