drawing off the spirit into the bottle, to speak in terms of our fairytale. But since body and soul, in spite of the artificial separation, are united in the mystery of life, the mercurial spirit, though imprisoned in the bottle, is yet found in the roots of the tree
Jung argues that the bottle enacts the alchemical separation of Mercurius from matter, equating the imprisoned spirit with the principle of ego-individuation as distinct from the supra-personal self.
, Alchemical Studies, 1967thesis