Mercurius is the divined winged Hermes manifest in matter, the god of revelation, lord of thought and sovereign psychopomp.
The liquid metal, argentum vivum -“living silver”, quick silver was the wonderful substance that perfectly expressed the nature of that which glistens and animates within.
When the alchemist speaks of Mercurius, on the face of it he means quick silver, but inwardly he means the world creating spirit concealed or imprisoned in matter. The dragon is probably the oldest pictorial symbol in alchemy of which we have documentary evidence.It
appears as the oupoBopoc, the tail eater, in the codex marcianus, which dates from the 10th or 11th century, together with the legend: (the one, the all). Time and again the alchemists reiterate that the opus proceeds from the one that leads back to the one, that it is a sort of circle like a dragon biting its own tail. For this reason the opus was often called circu (circular) or else rota (the wheel). Mercurius stands at the beginning and end of the work:
he is the prima materia, the caput corvi, the nigredo, as dragon he devours himself and as dragon he dies, to rise again as the lapis. He is the play of colours in the cauda pavonis and the division in to four elements. He is the hermaphrodite that was in the beginning, that splits in to the classical brother sister duality and is reunited in the coniunctio, to appear once again at the end in the radiant form of the lumen novum, the stone. He is metallic yet liquid, matter yet spirit, cold yet fiery, poison yet healing draught- a symbol uniting all opposites.