Milk occupies a surprisingly rich symbolic terrain in the depth-psychology corpus, functioning simultaneously as prima materia, sapientia, initiatory substance, and the most archaic vehicle of object-relations. Hillman offers the most philosophically elaborated treatment, reading milk as the alchemical ‘beginning, middle, and end’ — the substance that bridges the senex-puer polarity by grounding both in a primordial, pre-split nourishment that is neither regression nor mere dissolution but ‘tasted knowledge,’ sapor becoming sapientia. The alchemical literature, mediated through Abraham’s dictionary, compounds this by identifying milk — particularly ‘virgin’s milk’ — with the white mercurial tincture, the spiritual first distillate of the opus, and the medium of the chemical wedding. Neumann situates the milk-breast-cow complex at the deepest stratum of Great Mother symbolism, tracing its cultic instantiation in temple dairies of ancient Mesopotamia. Klein and Bion bring the term into clinical relief: for Klein, the sufficiency and timing of milk at the breast constitutes the original drama of persecutory and depressive anxiety, envy, and the first relation to the ‘good object’; for Bion, milk’s material delivery poses the epistemological question of what psychic faculty corresponds to the alimentary. Abraham (Karl) records the uncanny return of oral longing in depression. Von Franz’s fairy-tale material preserves a stranger folkloric usage: the milk-pond as a locus that is ‘beyond the problem of good and evil,’ where the hero must immerse himself to evade demonic capture. Kerenyi’s gold-leaf Orphic texts supply the most archaic layer — the initiate’s cry, ‘a kid, I fell into milk,’ marking apotheosis through dissolution in the divine substance.