As I have said, the confrontation with the unconscious usually begins in the realm of the personal unconscious, that is, of personally acquired contents which constitute the shadow, and from there leads to archetypal symbols which represent the collective unconscious.  The aim of the confrontation is to abolish the dissociation.  In order to reach this goal, either nature herself or medical intervention precipitates the conflict of opposites wihout whcih no union is possible.  This means not only bringing the conflict to consciousness; it also involves an expereince of a special kind, namely, the recognition of an alien "other" in oneself, or the objective presence of another will.  The alchmists, with astonishing accuracy, called this barely understandable thing Mercurius., in which concept they included all the statements which mythology and natural philosophy had ever made about him: he is God, daemon, person, thing, and the innermost secret in man; psychic as well as somatic.  He is himself the source of all opposites, since he is duplex and utriusque capax (capable of both).  This elusive intity symbolizes the unconscious in every particular, and a correct assessment of symbols leads to direct confrontation with it.

The Mercurius of the alchemists is a personification and concretization of what we today would call the collective unconscious.

Yet it would be an altogether unjustifiable suppression of the truth were I to confine myself to the negative description of Mercurius’ impish drolleries, his inexhaustible invention, his insinuations, his intriguing ideas and schemes, his ambivalence and – often – his unmistakable malice.  His is also capable of the exact opposite, … 

The Mercurius who personifies the unconscious is essentially “duplex,” paradoxically dualistic by nature, fiend, monster, beast, and at the same time panacea, “the philosophers’ son”. 

For the alchemists Paradise was a favourite symbol of the albedo, the regained state of innocence, and the source of its rivers is a symbol of the aqua permanens. For the Church Fathers Christ is this source, and Paradise means the ground of the soul from which the fourfold river of the Logos bubbles forth. Aion 235

Like the dragon, Mercurius is the slippery, evasive, poisonous, dangerous forerunner of the hermaphrodite, and for that reason he has to be overcome. Aion 234

As Mercurius is the principle name for the arcane substance, he deserves mention here as the paradox par excellence.  What is said of him is obviously true of the lapis, which is merely another synonym for the “thousand-named” arcane substance.  MC 44

   Ever since the Timaeus it has been repeatedly stated that the soul is a sphere. As the anima mundi, the soul revolves with the world wheel, whose hub is the Pole. That is why the “heart of Mercurius” is found there, for Mercurius is the anima mundi. The anima mundi is really the motor of the heavens.