The Fifth Essence—quintessentia in the Latin alchemical tradition—occupies a privileged position in the depth-psychological corpus as both a technical term imported from Paracelsian alchemy and a living symbol of psychological integration. Where the classical four elements (earth, water, fire, air) map onto Jung’s four psychological functions, the Fifth Essence names what supervenes upon their completion: a consolidated centre that is neither identical with any single function nor merely their aggregate, but the very principle of their unity. Von Franz, in her seminal exposition, articulates this most precisely: the quintessence is the four in one, and its attainment marks a qualitative threshold in individuation after which consciousness moves, in the text’s paradoxical formulation, ‘without movement.’ Edinger, reading the alchemical poetry of the Rosarium tradition, assigns the Fifth Essence to the ‘Fifth Circle’ and personifies it as the Crowned Maid—Luna transformed, the materiality principle sublimated. Jung himself, in his index entries and his treatment of Paracelsus, notes both the quinta essentia as an arcane remedy and the ‘spirit of the fifth essence’ as a distinct pneumatic agency. Across the corpus the term thus serves as a condensed symbol for the transcendent function, the philosopher’s stone as psychological telos, and the paradox of plurality resolved into unity.