The term ‘Dayworld’ enters depth-psychological discourse primarily through James Hillman’s 1979 work The Dream and the Underworld, where it functions as the structural counterpart — and conceptual adversary — of the underworld or nightworld. For Hillman, the dayworld designates the waking realm of ego-consciousness, temporal causality, solar rationality, and the compensatory logic that governs orthodox dream interpretation. His central polemical claim is that therapeutic practice has historically subjected the dream to the dayworld’s agenda, translating nocturnal imagery into waking-life utility rather than honoring the autonomous intentionality of the underworld. Andrew Samuels, in Jung and the Post-Jungians (1985), identifies Hillman’s dayworld/nightworld distinction as one of the three pivotal modifications to Jungian dream theory, noting that for Hillman the dream is not a compensatory communication directed toward dayworld ego-balance but a self-sufficient phenomenon obeying the primary-process laws of an entirely different ontological register. The tension between these two worlds is therefore not merely cosmological but methodological: it determines how the analyst behaves, what counts as insight, and whether the dream is permitted its own sovereign jurisdiction. The dayworld thus marks a site of epistemological contest within post-Jungian psychology, opposing hermeneutic strategies grounded in solar ego-consciousness to those that submit to chthonic, imaginal depth.