Within the depth-psychology corpus, ‘vein’ operates across several distinct registers that rarely intersect but collectively illuminate how Western and Eastern thought models the body as a conduit for non-material forces. In Platonic cosmology — most elaborately in the Timaeus — veins figure as hydraulic channels through which nourishment, blood, and quasi-spiritual substance are distributed in an irrigation system that prefigures later alchemical and psychological images of interior circulation. Plato’s explicit ignorance of cardiac muscle function means the vein, not the heart, bears primary responsibility for systemic movement, rendering it a passive conduit whose significance is organizational rather than vital. This hydraulic metaphor persists in Hillman’s reading of Harvey, where the clinical demonstration distinguishing veins from arteries marks the moment the heart ceases to be a seat of feeling and becomes a pump. A second, entirely distinct register appears in Kashmirian Tantra as mediated by Jaideva Singh’s commentary on the Vijñāna Bhairava: here the ‘central vein’ (suṣumnā) is the axis of contemplative ascent, the pathway along which breath ceases, kuṇḍalinī rises, and consciousness merges with Bhairava. A third, literalist register appears in psychopharmacological literature — Strassman and Maté — where the forearm vein receives intravenous substances, bridging biochemistry and consciousness research. The term thus spans cosmological plumbing, mystical anatomy, and clinical pharmacology.