SERPENT, IN ANCIENT RELIGIONS. - The cult of the serpent is quite widespread in the ancient religions and in those of primitive peoples, where it sometimes represents the supreme being who has the creative and destructive power of nature (Africa, Australia), especially insofar as it can give or deny rain; at other times, however, it hides or transforms itself under serpentine forms (e.g., Zeus Ctesios and Philios in Greece; Isis and Osiris in Egypt), or ends up entirely in the background, becoming an attribute of the god (e.g., Asclepius).
First of all, the serpent in myth has a cosmic value, since the creating or fashioning divinity of the world must struggle at the time of origins against a serpentine monster, always connected with the waters, in order to realize the cosmos from chaos, which is guarded by, or even identifies itself with, that serpent: such is the case of the Sumerian-Babylonian Tiamat, split open by Marduk (Enuma elish); of the Egyptian serpent Apophis and of the Hittite one Illuyankas, killed by the storm god Innaras; of the Vedic Vrtra (nicknamed Ahi = the enveloper) conquered by Indra, who was able to free the waters hidden by him (Rigveda I, 32); of the "world serpent" of the Nordic peoples (Edda, Volospa, 197 ff.) symbol of the Ocean that surrounds the Earth (Homer) and together with the serpentine monster Typhon conquered by Zeus. From these myths a twofold characteristic of the serpent is derived, as guardian of chaos, or, in a more archaic phase, as chaos itself; and from both these concepts derive in these ancient religions the other religious aspects of the serpent.
Thus, in the first place, its eternity, or at least immortality (a concept widely diffused in ethnology, perhaps born from the observation of the annual shedding of its skin), which it does not permit to belong also to man: such is the meaning of the Sumerian myth of Gilgamesh, who, having found after so many labors the herb of immortality, is robbed of it by a serpent (Epic of Gilgamesh, tablet 13, 304). Furthermore, it is the depositary of prophetic knowledge, for which it is used as an oracular instrument: at Delphi, in the very ancient oracle of Gaia, guarded by the serpent Python, later killed by Apollo; in the numerous medical oracles of Asclepius, and similarly at Rome with Aesculapius (cf. Pliny, VIII, 153); at Lanuvium in the temple of Juno a serpent served to ascertain the virginity of girls (Propertius, V, 8, 3); in the Edda the herbs of Sigurd understands the language of birds after having eaten the heart of the serpent Fafnir (Fafnismal, 148 ff.), etc. Medical science is also its characteristic: in Greece and at Rome the already mentioned medical oracles of Aesculapius where the serpent was the symbol of the god of medicine ("Inesse serpenti remedia multa creduntur et ideo Aesculapio dicatur"); for Rome one must also remember Bona Dea, in whose temple serpents were kept, and the goddess Salus with the attribute of the serpent; in Egypt some diseases were cured with the ashes of serpents.
Finally, one must remember the other important aspect of the serpent as genius loci: the serpent in fact, in archaic times guardian of chaos, preserves this characteristic of attachment to a place in order to guard and protect it ("Angues apud gentiles locorum erant pro geniis habiti semper": Isidore, Orig., 12, 4, 1); thus it is found very often guarding springs, altars, oracles and even cities (for example, the Acropolis of Athens was guarded by the serpent of Athena); but above all, it, connected with the infernal world, is the guardian of tombs in general and of the domestic hearth in particular, so much so as to symbolize the souls of the dead (Lares) and to be even venerated and kept in every house, as well as among primitive peoples, also in India, in Greece, at Rome, among the Slavs and the Balts.