" The development briefly outlined here seems to have been anticipated in medieval and Gnostic symbolism, just as the Antichrist was in the New Testament. How this occurred I will endeavour to describe in what follows. We have seen that, as the higher Adam corresponds to the lower, so the lower Adam corresponds to the serpent. For the mentality of the Middle Ages and of late antiquity, the first of the two double pyramids, the Anthropos Quaternio, represents the world of the spirit, or metaphysics, while the second, the Shadow Quaternio, represents sublunary nature and in particular man’s instinctual disposition, the “flesh”—to use a Gnostic-Christian term—which has its roots in the animal kingdom or, to be more precise, in the realm of warm-blooded animals. The nadir of this system is the cold-blooded vertebrate, the snake,30 for with the snake the psychic rapport that can be established with practically all warm-blooded animals comes to an end. That the snake, contrary to expectation, should be a counterpart of the Anthropos is corroborated by the fact—of especial significance for the Middle Ages—that it is on the one hand a well-known allegory of Christ, and on the other hand appears to be equipped with the gift of wisdom and of supreme spirituality.31 As Hippolytus says, the Gnostics identified the serpent with the spinal cord and the medulla. These are synonymous with the reflex functions. "

― C.G. Jung , Aion (Collected Works 9ii)