Mnemosyne — Memory personified — occupies a structurally pivotal position in the depth-psychology and classical scholarship corpus, functioning simultaneously as cosmogonic power, eschatological guardian, and the epistemological ground of inspired knowledge. The dominant treatment, developed with greatest rigor by Jean-Pierre Vernant, traces a decisive transformation across archaic and mystical traditions: in Hesiod and the epic poets, Mnemosyne is the omniscient mother of the Muses who transports the poet into direct presence with primeval time; in the Orphic tablets and Pythagorean eschatology, she becomes the post-mortem fountain whose waters confer immortality, set against Lethe’s oblivion, and whose mastery determines the soul’s liberation from the cycle of reincarnation. Marcel Detienne situates Mnemosyne within the functional triad of the archaic ‘masters of truth’ — poet, diviner, king — showing that her polar opposition to Lethe is ritually enacted at oracles such as Trophonios at Lebadeia. Jane Ellen Harrison reads that same polarity as a social-initiatory structure, while Bruno Snell emphasizes the Muses-as-daughters-of-Mnemosyne as the cognitive mechanism enlarging the poet’s recollection into divine omniscience. Vernant’s further argument — that the Platonic anamnesis transmits, via Pythagorean memory disciplines, the ancient mythical theme of Mnemosyne as fountain of inexhaustible life — makes the figure a hinge between archaic religion, mystery cult, and philosophical epistemology. Julian Jaynes alone dissents sharply, reading the Muses as genuine auditory hallucinations of bicameral men, not symbolic memory-figures.