Surface Illumination occupies a liminal position in the depth-psychology corpus, functioning simultaneously as a physical phenomenon and a metaphysical category. The term surfaces most sharply in the Plotinian tradition, where light’s capacity to fall upon and transform corporeal surfaces opens onto questions about the ontological status of illumination itself: is it a quality inhering in matter, an activity emanating from a luminous source, or a dynamic relation between the two? Plotinus presses this question to its limit, asking whether light requires a material substrate or can overleap a void entirely. In Simondon, surface illumination is recast in the language of wave-particle physics, where the concentration or diffusion of light across a surface unit becomes a measure of discontinuous energy exchange — the surface itself functioning as the locus of quantum individuation. The Taoist commentators of the I Ching, particularly Liu I-ming, translate the problem into an alchemical register: the concealment or revelation of inner illumination constitutes the practitioner’s fundamental ethical and cosmological task, in which surface radiance is always either the symptom of premature expenditure or the sign of properly nurtured inner fire. Hillman and Huxley introduce the phenomenological and cultural dimensions, treating artificial surface illumination as an agent that generates atmosphere, interiority, and preternatural significance. Corbin bridges these poles by identifying surface luminescence — the nimbus, the aura — as the exterior inscription of the Xvarnah, an inward light of glory made visible.