The term ‘Monad’ occupies a pivotal and richly contested position across the depth-psychology corpus, appearing at the intersection of Gnostic cosmology, Leibnizian metaphysics, Jaina ontology, and Jungian self-psychology. Jung himself engages the term most directly in its Gnostic register, where the Monad figures as a luminous atom of the Deity — a ‘spark of light’ (σπινθήρ) dwelling within the Setheus creator — and as a cosmological cipher for the divine ground of selfhood. This Gnostic Monad maps readily onto Jung’s conception of the Self as indivisible psychic totality, and Hippolytus’s account of Monoïmos provides Jung with the ‘indivisible point’ (ἀμέριστος στιγμή) that coheres with the mandala symbolism. Leibniz enters the conversation through Jung’s reflections on synchronicity and the collective unconscious: the windowless monad, a ‘perpetual living mirror of the universe,’ anticipates the microcosm-macrocosm logic underwriting analytical psychology’s deepest claims. Rudhyar transposes the term into an astrological-vitalist key, treating the monad as the qualitative imprint of the founding moment of any living whole. Zimmer documents the Jaina life-monad (jīva) with scholarly precision, contrasting its quasi-material karmic contamination with the Sāṅkhya-Yoga view of the life-monad as eternally free illusion. Hillman, characteristically, aligns the monad with Leibniz’s entelechy and Jung’s Self as converging fantasies of psychic independence. The tensions between these positions — cosmological, metaphysical, biological, and psychological — make ‘Monad’ one of the corpus’s richest convergence points.