The snake in alchemy is the “mercurial serpent”, the old Gnostic image for the Nous, the mind, where the spirit was represented as a serpent, as the Agathodaemon (the good daemon), or directly called the serpent of the Nous. ~Carl Jung, ETH, Alchemy, Page 215.
The dead in general are frequently depicted as snakes. Like the “hero” of alchemy, Mercurius, another ancient alchemical authority, the Agathodaimon, also has the form of a snake ~Carl Jung, CW 14 Para 481
In St. Ambrose the “serpent hung on the wood” is a “typus Christi,” as is the “brazen serpent on the cross” in Albertus Magnus. Christ as Logos is synonymous with the Naas, the serpent of the Nous among the Ophites. The Agathodaimon (good spirit) had the form of a snake, and in Philo the snake was considered the “most spiritual” animal. On the other hand, its cold blood and inferior brain-organization do not suggest any noticeable degree of conscious development, while its unrelatedness to man makes it an alien creature that arouses his fear and yet fascinates him ~Carl Jung, CW 13, Para 448
The hero is himself the snake, himself the sacrificer and the sacrificed, which is why Christ rightly compares himself with the healing Moses-serpent (fig. 258.09b) and why the saviour of the Christian Ophites was a serpent, too. It is both Agathodaimon (fig. 037) and Cacodaimon. In German legend we are told that the heroes have snake’s eyes ~Carl Jung, CW 5, Para 593
He [the hero] shares this paradoxical nature with the snake. According to Philo the snake is the most spiritual of all creatures; it is of a fiery nature, and its swiftness is terrible. It has a long life and sloughs off old age with its skin. In actual fact the snake is a cold-blooded creature, unconscious and unrelated. It is both toxic and prophylactic, equally a symbol of the good and bad daemon (the Agathodaimon), of Christ and the devil. Among the Gnostics it was regarded as an emblem of the brain-stem and spinal cord, as is consistent with its predominantly reflex psyche. It is an excellent symbol for the unconscious, perfectly expressing the latter’s sudden and unexpected manifestations, its painful and dangerous intervention in our affairs, and its frightening effects ~Carl Jung, CW 5, Para 580
The hero is himself the snake, himself the sacrificer and the sacrificed, which is why Christ rightly compares himself with the healing Moses-serpent and why the saviour of the Christian Ophites was a serpent, too. It is both Agathodaimon and Cacodaimon. In German legend we are told that the heroes have snake’s eyes ~Carl Jung, CW 5, Para 593
Tum was chiefly worshipped as the Agathodaimon serpent, of whom it was said: “The sacred Agathodaimon serpent goes forth from the city of Nezi.” The snake, because it casts its skin, is a symbol of renewal, like the scarab beetle, a sun-symbol, which was believed to be of masculine sex only and to beget itself ~Carl Jung, CW 5, Para 410