The term ‘Master and Emissary’ enters the depth-psychology corpus primarily through Iain McGilchrist’s landmark 2009 work of that name, wherein it serves as a governing metaphor for the asymmetrical relationship between the brain’s two hemispheres. McGilchrist argues that the right hemisphere — the Master — possesses a broader, more contextually attuned mode of apprehension, while the left hemisphere — the Emissary — is constitutionally suited to detailed, instrumental manipulation of what the right hemisphere first grasps. The danger McGilchrist identifies is structural usurpation: the Emissary, gifted in articulation and systematisation, progressively displaces the Master, with catastrophic consequences for culture, science, and selfhood. This metaphor is elaborated across McGilchrist’s subsequent volume, ‘The Matter with Things’ (2021), where left-hemisphere dominance is diagnosed as the operative pathology of Western modernity. The corpus surrounding this term reveals related preoccupations in other traditions: Sufi psychology speaks of the inner master and the disciple’s surrender, Zen literature explores the authority of the master-teacher who catalyses awakening, and Gnostic sources describe emissary-figures dispatched into a fallen world to retrieve the soul. These parallel structures illuminate the depth-psychological resonance McGilchrist’s neurological allegory carries — a resonance that extends well beyond brain science into questions of orientation, wholeness, and epistemic humility.