Within the depth-psychology corpus, ‘sap’ operates along several distinct but interrelated axes. Most fundamentally, it appears in Onians’s philological archaeology of archaic physiology, where sap belongs to a constellation of vital fluids—seed, cerebro-spinal fluid, synovial fluid, sweat—understood as the very stuff of life-force, consciousness, and generative power. The Old Icelandic safi (‘sap’) and sefi (‘mind’) are shown to be cognate, establishing an etymological bridge between vegetable vitality and psychic intelligence that illuminates the Latin sapere and sapiens. In alchemical literature, treated extensively by Abraham, Jung, and von Franz, sap assumes a more symbolic register: the congealed sap of the philosophical tree becomes amber-gold, the coagulated essence of the opus, a potent emblem of the lapis. Onians further documents funeral rites in which oily sap—along with myrrh and other arboreal exudations—was offered to the dead as compensatory life-fluid, sucus replacing what the departed had lost. Hillman draws the sapor/sapientia connection into his senex-puer phenomenology, treating ‘tasted knowledge’ as the milk of true wisdom that dissolves Saturnine rigidity. The term thus traverses physiology, etymology, alchemy, and archetypal psychology, always circling the question of how vital substance becomes mind.