The threshold of consciousness stands as one of the most technically precise and theoretically freighted concepts in the depth-psychological corpus. Jung employs it with deliberate rigor as an energic metaphor: psychic contents become subliminal — and therefore unconscious — through loss of energy, while unconscious processes ascend into awareness through accretion of energy. The concept thus presupposes an energic model of psychic functioning, and Jung was careful to note that this very presupposition carries philosophical difficulties, since positing a threshold implies an experiencing subject on both sides of the divide. For Jung, the threshold also enables the theoretical possibility of unconscious volition — contents that possess sufficient energy to achieve at least a ‘secondary consciousness’ without fully entering the primary field of the ego. Complementing this, Jung identifies active imagination as the privileged method for accessing material lying ‘immediately below the threshold,’ material most prone to spontaneous irruption. The Jungian corpus is in dialogue here with broader psychological tradition: the threshold concept derives partly from the Herbartian and then Fechnerian psychophysics absorbed into nineteenth-century German psychology, and it shapes how both Freud and post-Freudian analysts theorize repression, resistance, and the subliminal. Neuroscientific voices — Damasio, LeDoux, Jaynes — reframe the threshold in terms of wakefulness, neural correlates, and reportability, often questioning whether the boundary is categorical or continuous. The term thus anchors debates about the architecture of mind that traverse psychoanalysis, analytical psychology, and cognitive neuroscience alike.