Within the depth-psychology corpus, ‘Mare’ operates on at least three distinct registers that the scholarly literature holds in productive tension. The first is etymological and daemonological: Jung’s ‘Symbols of Transformation’ traces the Indo-European root *mer/*mor (‘to die’) through the Germanic Mara and the Latin mors, arguing that the nightmare-figure who treads sleepers to death is a personification of fate cognate with the Moirai, the matres, and the matronae — thus binding the nocturnal incubus directly to the archetype of the devouring mother. The second register is symbolic and mythological: Demeter’s theriomorphic manifestation as a mare (attested in Kerényi and the Jungian–Kerényi collaborative volume) locates the mare within the grain-goddess and underworld-mother complex, making it an avatar of chthonic fertility. The third register is cosmological and hexagrammatic: the I Ching commentary tradition (both Richard Wilhelm and Hellmut Wilhelm) assigns the mare as the proper animal-symbol of the Receptive hexagram K’un — strong, swift, gentle, devoted, emblematic of earth-consciousness rather than heaven’s creative dragon. Jung’s fairy-tale analysis in ‘The Archetypes and the Collective Unconscious’ synthesises these streams, reading the three-legged mare as simultaneously Princess B and the shadow of the anima. The term thus stands at the intersection of archetype, etymology, fate, and feminine symbolism.