Cross-cultural symbolic values
The serpent is one of the oldest and most widespread mythological symbols. Considerable overlap exists in the symbolic values that serpents represent in various cultures. Some such overlap is due to the common historical ancestry of contemporary symbols. Much of the overlap, however, is traceable to the common biological characteristics of snakes.
In some instances, serpents serve as positive symbols with whom it is possible to identify or to sympathize; in other instances, serpents serve as negative symbols, representing opponents or antagonists of figures or principles with which it is possible to identify. Serpents also appear as ambivalent figures, neither wholly positive nor wholly negative in valence. An example of a serpent used as a positive symbol is Mucalinda, the king of snakes who shielded the Buddha from the elements as the Buddha sat in meditation. An example of a serpent used as a negative symbol is the snake who tempted Adam and Eve in the Garden of Eden, as described in the Book of Genesis.
The following are some of the particular symbolic values frequently assiged to serpents in myth, legend, and literature:
In the Abrahamic religions, serpents are connected with deceit, and are used to symbolize deceitfulness. An example is the serpent in the Garden of Eden, who tricks the Adam and Eve into partaking of the Fruit of the Tree of the Knowledge of Good and Evil.
The symbolic connection between serpents and deceit may depend in part on the observation that snakes have forked tongues. A forked tongue is a tongue which has not one end, but two, pointing in different directions. In humans, the tongue is an essential tool in speech, and the presence of only one tip signifies the unity of truthful speech, and corresponds to the unity of the truth itself. There is only one truth, but there are many lies. The forked tongue represents the disunity of deceitful speech.
Serpents are represented as potent guardians of temples and other sacred spaces. This connection may be grounded in the observation that when threatened, some snakes (such as rattlesnakes or cobras) frequently hold and defend their ground, first resorting to threatening display and then fighting, rather than retreat. Thus, they are natural guardians of treasures or sacred sites which cannot easily be moved out of harm's way.
At Angkor in Cambodia, numerous stone sculptures present hooded multi-headed nagas as guardians of temples or other premises. A favorite motif of Angkorean sculptors from approximately the 12th century A.D. onward was that of the Buddha, sitting in the position of meditation, his weight supported by the coils of a multi-headed naga that also uses its flared hood to shield him from above. This motif recalls the story of the Buddha and the serpent king Mucalinda: as the Buddha sat beneath a tree engrossed in meditation, Mucalinda came up from the roots of the tree to shield the Buddha from a tempest that was just beginning to arise.
The Gadsden flag of the American Revolution depicts a rattlesnake coiled up and poised to strike. Below the image of the snake is the legend, "Don't tread on me." The snake symbolized the willingness of the colonists to fight for their rights and homeland.
 Poison and medicine
Serpents are connected with poison and medicine. The snake's venom is associated with the chemicals of plants and fungi  that have the power to either heal, poison or provide expanded consciousness (and even the elixir of life and immortality) through divine intoxication. Because of its herbal knowledge and entheogenic association the snake was often considered one of the wisest animals, being (close to the) divine. Its divine aspect combined with its habitat in the earth between the roots of plants made it an animal with chthonic properties connected to the afterlife and immortality.
 Renewal, rebirth, regeneration
Serpents are connected with renewal or regeneration. This trait is connected with the practice of snakes of shedding their old skin and growing a new one.
 Vengefulness and vindictiveness
Serpents are connected with vengefulness and vindictiveness. This connection depends in part on the experience that poisonous snakes often deliver deadly defensive bites without giving prior notice or warning to their unwitting victims. Although a snake is defending itself from the encroachment of its victim into the snake's immediate vicinity, the unannounced and deadly strike may seem unduly vengeful when measured against the unwitting victim's perceived lack of blameworthiness.
Edgar Allan Poe's famous short story "The Cask of Amontillado" invokes the image of the serpent as a symbol for petty vengefulness. The story is told from the point of view of the vindictive Montressor, who hatches a secret plot to murder his rival Fortunato in order to avenge real or imagined insults. Before carrying out his scheme, Montresor reveals his family's coat-of-arms to the intended victim: "A huge human foot d'or, in a field azure; the foot crushes a serpent rampant whose fangs are imbedded in the heel." Fortunato, not suspecting that he has offended Montressor, fails to understand the symbolic import of the coat-of-arms, and blunders onward into Montresor's trap.
 Mythological serpents
Sometimes serpents and dragons are used interchangeably, having similar symbolic functions. The venom of the serpent is thought to have a fiery quality similar to a fire spitting dragon. The Greek Ladon and the Norse Níðhöggr are sometimes described as serpents and sometimes as dragons. In Germanic mythology, serpent (Old English: wyrm, Old High German: wurm, Old Norse: ormr) is used interchangeable with the Greek borrowing dragon (OE: draca, OHG: trahho, ON: dreki). In China, the Indian serpent nāga was equated with the lóng or Chinese dragon. The Aztec and Toltec serpent god Quetzalcoatl also has dragon like wings, like its equivalent in Mayan mythology Gukumatz ("feathered serpent").
 Sea serpents
Sea serpents were giant cryptozoological creatures once believed to live in water, whether sea monsters such as the Leviathan or lake monsters such as the Loch Ness Monster. If they were referred to as "sea snakes", they were understood to be the actual snakes that live in Indo-Pacific waters (Family Hydrophiidae).
 Cosmic serpents
The serpent, when forming a ring with its tail in its mouth, is a clear and widespread symbol of the "All-in-All", the totality of existence, infinity and the cyclic nature of the cosmos. The most well known version of this is the Aegypto-Greek Ourobouros. It is believed to have been inspired by the Milky Way as some ancient texts refer to a serpent of light residing in the heavens. The Ancient Egyptians associated it with Wadjet, one of their oldest deities as well as another aspect, Hathor.
In Hindu mythology Vishnu is said to sleep while floating on the cosmic waters on the serpent Shesha. In the Puranas Shesha holds all the planets of the universe on his hoods and to constantly sing the glories of Vishnu from all his mouths. He is sometimes referred to as "Ananta-Shesha" which means "Endless Shesha." In the Samudra manthan chapter of the Puranas, Shesha loosens Mount Mandara for it to be used as a churning rod by the Asuras and Devas to churn the ocean of milk in the heavens in order to make Soma (or Amrita), the divine elixir of immortality. As a churning rope another giant serpent called Vasuki is used.
In pre-Columbian Central America Quetzalcoatl was sometimes depicted as biting its own tail. The mother of Quetzalcoatl was the Aztec goddess Coatlicue ("the one with the skirt of serpents"), also known as Cihuacoatl ("The Lady of the serpent"). Quetzalcoatl's father was Mixcoatl ("Cloud Serpent"). He was identified with the Milky Way, the stars and the heavens in several Mesoamerican cultures.
The demi-god Aidophedo of the West African Ashanti is also a serpent biting its own tail. In Dahomey mythology of Benin in West Africa, the serpent that supports everything on its many coils was named Dan. In the Vodou of Benin and Haiti Ayida-Weddo (a.k.a. Aida-Wedo, Aido Quedo, "Rainbow-Serpent") is a spirit of fertility, rainbows and snakes, and a companion or wife to Dan, the father of all spirits. As Vodou was exported to Haiti through the slave trade Dan became Danballah, Damballah or Damballah-Wedo. Because of his association with snakes, he is sometimes disguised as Moses, who carried a snake on his staff. He is also thought by many to be the same entity of Saint Patrick, known as a snake banisher.
The serpent Hydra is a star constellation representing either the serpent thrown angrily into the sky by Apollo or the Lernaean Hydra as defeated by Heracles for one of his Twelve Labours. The constellation Serpens represents a snake being tamed by Ophiuchus the snake-handler, another constellation. The most probable interpretation is that Ophiuchus represents the healer Asclepius.
 Chthonic serpents and sacred trees
In many myths the chthonic serpent (sometimes a pair) lives in or is coiled around a Tree of Life situated in a divine garden. In the Genesis story of the Torah and Biblical Old Testament the Tree of the Knowledge of Good and Evil is situated in the Garden of Eden together with the tree of immortality. In Greek mythology Ladon coiled around the tree in the garden of the Hesperides protecting the entheogenic golden apples.
Under yet another Tree (the Bodhi tree of Enlightenment), the Buddha sat in ecstatic meditation. When a storm arose, the mighty serpent king Mucalinda rose up from his place beneath the earth and enveloped the Buddha in seven coils for seven days, not to break his ecstatic state.
The Vision Serpent was also a symbol of rebirth in Mayan mythology, fuelling some cross-Atlantic cultural contexts favored in pseudoarchaeology. The Vision Serpent goes back to earlier Maya conceptions, and lies at the center of the world as the Mayans conceived it. "It is in the center axis atop the World Tree. Essentially the World Tree and the Vision Serpent, representing the king, created the center axis which communicates between the spiritual and the earthly worlds or planes. It is through ritual that the king could bring the center axis into existence in the temples and create a doorway to the spiritual world, and with it power". (Schele and Friedel, 1990: 68)
Sometimes the Tree of Life is represented (in a combination with similar concepts such as the World Tree and Axis mundi or "World Axis") by a staff such as those used by shamans. Examples of such staffs featuring coiled snakes in mythology are the caduceus of Hermes, the Rod of Asclepius, the staff of Moses, and the papyrus reeds and deity poles entwined by a single serpent Wadjet, dating to earlier than 3000 BCE. The oldest known representation of two snakes entwined around a rod is that of the Sumerian fertility god Ningizzida. Ningizzida was sometimes depicted as a serpent with a human head, eventually becoming a god of healing and magic. It is the companion of Dumuzi (Tammuz) with whom it stood at the gate of heaven. In the Louvre, there is a famous green steatite vase carved for king Gudea of Lagash (dated variously 2200–2025 BCE) with an inscription dedicated to Ningizzida. Ningizzida was the ancestor of Gilgamesh, who according to the epic dived to the bottom of the waters to retrieve the plant of life. But while he rested from his labor, a serpent came and ate the plant. The snake became immortal, and Gilgamesh was destined to die.
Ningizzida has been popularised in the 20th C. by Raku Kei Reiki (a.k.a. "The Way of the Fire Dragon") where "Nin Giz Zida" is believed to be a fire serpent of Tibetan rather than Sumerian origin. Nin Giz Zida is another name for the ancient Hindu concept of Kundalini, a Sanskrit word meaning either "coiled up" or "coiling like a snake". Kundalini refers to the mothering intelligence behind yogic awakening and spiritual maturation leading to altered states of consciousness. There are a number of other translations of the term usually emphasizing a more serpentine nature to the word— e.g. 'serpent power'. It has been suggested by Joseph Campbell that the symbol of snakes coiled around a staff is an ancient representation of Kundalini physiology. The staff represents the spinal column with the snake(s) being energy channels. In the case of two coiled snakes they usually cross each other seven times, a possible reference to the seven energy centers called chakras.
In Ancient Egypt, where the earliest written cultural records exist, the serpent appears from the beginning to the end of their mythology. Ra and Atum ("he who completes or perfects") became the same god, Atum, the "counter-Ra," was associated with earth animals, including the serpent: Nehebkau ("he who harnesses the souls") was the two headed serpent deity who guarded the entrance to the underworld. He is often seen as the son of the snake goddess Renenutet. She often was confused with (and later was absorbed by) their primal snake goddess Wadjet, the Egyptian cobra, who from the earliest of records was the patron and protector of the country, all other deities, and the pharaohs. Hers is the first known oracle. She was depicted as the crown of Egypt, entwined around the staff of papyrus and the pole that indicated the status of all other deities, as well as having the all-seeing eye of wisdom and vengeance. She never lost her position in the Egyptian pantheon.
The image of the serpent as the embodiment of the wisdom transmitted by Sophia was an emblem used by gnosticism, especially those sects that the more orthodox characterized as "Ophites" ("Serpent People"). The chthonic serpent was one of the earth-animals associated with the cult of Mithras. The Basilisk, the venomous "king of serpents" with the glance that kills, was hatched by a serpent, Pliny the Elder and others thought, from the egg of a cock.
The Rainbow Serpent (also known as the Rainbow Snake) is a major mythological being for Aboriginal people across Australia, although the creation myth associated with it are best known from northern Australia. In Fiji Ratumaibulu was a serpent god who ruled the underworld and made fruit trees bloom.
 Serpents in other religious and cultural traditions
 Hindu and Buddhist mythology
Nāga (Sanskrit:नाग) is the Sanskrit and Pāli word for a deity or class of entity or being, taking the form of a very large snake, found in Hinduism and Buddhism. The use of the term nāga is often ambiguous, as the word may also refer, in similar contexts, to one of several human tribes known as or nicknamed "Nāgas"; to elephants; and to ordinary snakes, particularly the King Cobra and the Indian Cobra, the latter of which is still called nāg in Hindi and other languages of India. A female nāga is a nāgī. The Snake primarily represents rebirth, death and mortality, due to its casting of its skin and being symolically "reborn".
 Cambodian mythology
Serpents, or nagas, play a particularly important role in Cambodian mythology. A well-known story explains the emergence of the Khmer people from the union of Indian and indigenous elements, the latter being represented as nagas. According to the story, an Indian brahmana named Kaundinya came to Cambodia, which at the time was under the dominion of the naga king. The naga princess Soma sallied forth to fight against the invader but was defeated. Presented with the option of marrying the victorious Kaundinya, Soma readily agreed to do so, and together they ruled the land. The Khmer people are their descendants.
 Greek mythology
- See also: Dragons in Greek mythology
Serpents figured prominently in archaic Greek myths. According to some sources, Ophion ("serpent", a.k.a. Ophioneus), ruled the world with Eurynome before the two of them were cast down by Cronus and Rhea. The oracles of the Ancient Greeks were said to have been the continuation of the tradition begun with the worship of the Egyptian cobra goddess, Wadjet.
The Minoan Snake Goddess brandished a serpent in either hand, perhaps evoking her role as source of wisdom, rather than her role as Mistress of the Animals (Potnia theron), with a leopard under each arm. She is a Minoan version of the Canaanite fertility goddess Asherah. It is not by accident that later the infant Heracles, a liminal hero on the threshold between the old ways and the new Olympian world, also brandished the two serpents that "threatened" him in his cradle. Classical Greeks did not perceive that the threat was merely the threat of wisdom. But the gesture is the same as that of the Cretan goddess.
Typhon the enemy of the Olympian gods is described as a vast grisly monster with a hundred heads and a hundred serpents issuing from his thighs, who was conquered and cast into Tartarus by Zeus, or confined beneath volcanic regions, where he is the cause of eruptions. Typhon is thus the chthonic figuration of volcanic forces. Amongst his children by Echidna are Cerberus (a monstrous three-headed dog with a snake for a tail and a serpentine mane), the serpent tailed Chimaera, the serpent-like chthonic water beast Lernaean Hydra and the hundred-headed serpentine dragon Ladon. Both the Lernaean Hydra and Ladon were slain by Heracles.
Python was the earth-dragon of Delphi, she always was represented in the vase-paintings and by sculptors as a serpent. Pytho was the chthonic enemy of Apollo, who slew her and remade her former home his own oracle, the most famous in Classical Greece.
Amphisbaena a Greek word, from amphis, meaning "both ways", and bainein, meaning "to go", also called the "Mother of Ants", is a mythological, ant-eating serpent with a head at each end. According to Greek mythology, the mythological amphisbaena was spawned from the blood that dripped from Medusa the Gorgon's head as Perseus flew over the Libyan Desert with her head in his hand.
Medusa and the other Gorgons were vicious female monsters with sharp fangs and hair of living, venomous snakes whose origins predate the written myths of Greece and who were the protectors of the most ancient ritual secrets. The Gorgons wore a belt of two intertwined serpents in the same configuration of the caduceus. The Gorgon was placed at the highest point and central of the relief on the Parthenon.
Asclepius, the son of Apollo and Koronis, learned the secrets of keeping death at bay after observing one serpent bringing another (which Asclepius himself had fatally wounded) healing herbs. To prevent the entire human race from becoming immortal under Asclepius's care, Zeus killed him with a bolt of lightning. Asclepius' death at the hands of Zeus illustrates man's inability to challenge the natural order that separates mortal men from the gods. In honor of Asclepius, snakes were often used in healing rituals. Non-poisonous snakes were left to crawl on the floor in dormitories where the sick and injured slept. In The Library, Apollodorus claimed that Athena gave Asclepius a vial of blood from the Gorgons. Gorgon blood had magical properties: if taken from the left side of the Gorgon, it was a fatal poison; from the right side, the blood was capable of bringing the dead back to life. However Euripides wrote in his tragedy Ion that the Athenian queen Creusa had inherited this vial from her ancestor Erichthonios, who was a snake himself and receiving the vial from Athena. In this version the blood of Medusa had the healing power while the lethal poison originated from Medusa's serpents.
Laocoön was allegedly a priest of Poseidon (or of Apollo, by some accounts) at Troy; he was famous for warning the Trojans in vain against accepting the Trojan Horse from the Greeks, and for his subsequent divine execution. Poseidon (some say Athena), who was supporting the Greeks, subsequently sent sea-serpents to strangle Laocoön and his two sons, Antiphantes and Thymbraeus. Another tradition states that Apollo sent the serpents for an unrelated offense, and only unlucky timing caused the Trojans to misinterpret them as punishment for striking the Horse.
Olympias, the mother of Alexander the Great and a princess of the primitive land of Epirus, had the reputation of a snake-handler, and it was in serpent form that Zeus was said to have fathered Alexander upon her; tame snakes were still to be found at Macedonian Pella in the 2nd century AD (Lucian, Alexander the false prophet) and at Ostia a bas-relief shows paired coiled serpents flanking a dressed altar, symbols or embodiments of the Lares of the household, worthy of veneration (Veyne 1987 illus p 211).
Aeetes, the king of Colchis and father of the sorceress Medea, possessed the Golden Fleece. He guarded it with a massive serpent that never slept. Medea, who had fallen in love with Jason of the Argonauts, enchanted it to sleep so Jason could seize the Fleece.
 Norse mythology
- See also: Jörmungandr
According to the Prose Edda, Odin took Loki's three children, Fenrisúlfr, Hel and Jörmungandr. He tossed Jörmungandr into the great ocean that encircles Midgard. The serpent grew so big that he was able to surround the Earth and grasp his own tail, and as a result he earned the alternate name of the Midgard Serpent or World Serpent. Jörmungandr's arch enemy is the god Thor.
 Judaic and Christian symbolism
In the Hebrew Bible (the Tanach) of Judaism, the serpent (Hebrew nahash נחש) in the Garden of Eden lured Eve with the promise of forbidden knowledge, and denying her mortality would be a result. Though not initially identified with Satan (adversary) in the Book of Genesis, the serpent is later cursed as an adversary of Eve's offspring. "Now the serpent was more cunning than any beast of the field which the Lord God had made," Genesis 3:1 reminded its readers. "Cunning" is a sound-alike pun on the word for "Naked." Nor is there any indication in Genesis that the Serpent was a deity in its own right, aside from the fact that there are only two cases of animals that talk in the Pentateuch. (Balaam's ass being the other) Although the identity of the Serpent as Satan is made explicit the Christian Book of Revelation, in Genesis the Serpent is merely portrayed as a deceptive creature or trickster, promoting as good what God had directly forbidden, and particularly cunning in its deception. (cf. Gen. 3:4-5 and 3:22)
The staff of Moses transformed into a snake and then back into a staff; according to Islamic, Christian, and Jewish hagiography:
- And the Lord said unto him, What is that in thine hand? And he said, A rod. And he said, Cast it on the ground. And he cast it on the ground, and it became a serpent; and Moses fled from before it. And the Lord said unto Moses, Put forth thine hand, and take it by the tail. And he put forth his hand and caught it and it became a rod in his hand. (Exodus 4:2-4)
- "21.6. And the Lord sent fiery serpents among the people, and they bit the people; and much people of Israel died. 7. Therefore the people came to Moses, and said, We have sinned, for we have spoken against the Lord, and against thee; pray unto the Lord, that he take away the serpents from us. And Moses prayed for the people. 8. And the Lord said unto Moses, Make thee a fiery serpent, and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live. 9. And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived." (Book of Numbers 21:6-9)
When the reformer King Hezekiah came to the throne of Judah in the late 8th century BCE:
- "He removed the high places, and brake the images, and cut down the groves, and brake in pieces the brasen serpent that Moses had made: for unto those days the children of Israel did burn incense to it: and he called it Nehushtan." 2 Kings 18:4.
In Christianity, a connection between the Serpent and Satan is strongly made, and Genesis 3:14 where God curses the serpent, is seen in that light: "And the LORD God said unto the serpent, Because thou hast done this, thou art cursed above all cattle, and above every beast of the field; upon thy belly shalt thou go, and dust shalt thou eat all the days of thy life". Some feel that this seems to indicate that the serpent had legs prior to this punishment. But if the lying serpent was in fact Satan himself (as he is called THE serpent or dragon), rather than an ordinary snake simply possessed by Satan, then the reference to crawling and dust is purely symbolic reference to his ultimate humiliation and defeat.
In the Gospel of Matthew 3:7, John the Baptist calls the Pharisees and Saducees visiting him a "brood of vipers". Later in Matthew 23:33, Jesus himself uses this imagery, observing: "Ye serpents, ye generation of vipers, how can ye escape the damnation of Gehenna?" ("Hell" is the usual translation of Jesus' word Gehenna.)
Although in the minority, there are at least a couple of passages in the New Testament that do not present the snake with negative connotation. When sending out the twelve apostles, Jesus exhorted them "Behold, I send you forth as sheep in the midst of wolves: be ye therefore wise as serpents, and harmless as doves" (Matthew 10:16).
Jesus made a comparison between himself and the setting up of the snake on the hill in the desert by Moses:
- And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: That whosoever believeth in him should not perish, but have eternal life (John 3:14-15).
In this comparison Jesus was not so much connecting himself to the serpent, but showing the analogy of his being a divinely provided object of faith, through which God would provide salvation, just as God provided healing to those who looked in faith to the brass serpent.
The other most significant reference to the serpent in the New Testament occurs in Revelation 20:2, where the identity of the serpent in Genesis is made explicit:
- "The great dragon was hurled down -- that ancient serpent called the devil, or Satan, who leads the whole world astray..."
This verse lends support to the view that of the serpent being Satan himself, which helps to explain, as well, why Eve was not surprised to be spoken to by the serpent -- it was not a talking snake, but a beautiful and intelligent (yet evil) angelic being.
- Veyne, Paul, 1987. A History of Private Life : 1. From Pagan Rome to Byzantium
Snake handling is a religious ritual in a small number of Christian churches in the U.S., usually characterized as rural and Pentecostal. Practitioners believe it dates to antiquity and quote the Bible to support the practice, especially:
- "And these signs shall follow them that believe: In my name shall they cast out devils; they shall speak with new tongues. They shall take up serpents; and if they drink any deadly thing, it shall not hurt them; they shall lay hands on the sick, and they shall recover." (Mark 16:17-18)
- "Behold, I give unto you power to tread on serpents and scorpions, and over all the power of the enemy: and nothing shall by any means hurt you." (Luke 10:19)
According to Joseph Campbell's Occidental Mythology, Yahweh is believed to have originated as a serpent consort of the Jewish earth mother goddess Asherah. This is reflected in the identity of Yahweh with the Egyptian Set, and the similarity of practices between Egyptian Set worship and Judaism, such as the sacrifice of the red heifer (detailed in Plutarch's Isis and Osiris), as well the identity between Yahweh and the snake-legged Greek Typhon, whose snake-legged image appears with the name "Ia", "Iah" or "Yah" on many amulets and charms found among the graves of the Maccabees (also Campbell).
 Native North American mythology
In one Native American story, an evil serpent kills one of the gods' cousins, so the god kills the serpent in revenge. But the dying serpent unleashes a great flood. People first flee to the mountains and then, when the mountains are covered, they float on a raft until the flood subsides. The evil spirits that the serpent god controlled then hide out of fear. The Mound Builders associated great mystical value to the serpent, as the Serpent Mound demonstrates, though we are unable to unravel the particular associations.
 Modern medicine
Snakes entwined the staffs both of Hermes (the caduceus) and of Asclepius, where a single snake entwined the rough staff. On Hermes' caduceus, the snakes were not merely duplicated for symmetry, they were paired opposites. (This motif is congruent with the phurba.) The wings at the head of the staff identified it as belonging to the winged messenger, Hermes, the Roman Mercury, who was the god of magic, diplomacy and rhetoric, of inventions and discoveries, the protector both of merchants and that allied occupation, to the mythographers' view, of thieves. It is however Hermes' role as psychopomp, the escort of newly-deceased souls to the afterlife, that explains the origin of the snakes in the caduceus since this was also the role of the Sumerian entwined serpent god Ningizzida, with whom Hermes has sometimes been equated.
In Late Antiquity, as the arcane study of alchemy developed, Mercury was understood to be the protector of those arts too and of arcane or occult "Hermetic' information in general. Chemistry and medicines linked the rod of Hermes with the staff of the healer Asclepius, which was wound with a serpent; it was conflated with Mercury's rod, and the modern medical symbol— which should simply be the rod of Asclepius— often became Mercury's wand of commerce. Another version is used in alchemy whereas the snake is crucified, known as Nicolas Flamel's caduceus. Art historian Walter J. Friedlander, in The Golden Wand of Medicine: A History of the Caduceus Symbol in Medicine (1992) collected hundreds of examples of the caduceus and the rod of Asclepius and found that professional associations were just somewhat more likely to use the staff of Asclepius, while commercial organizations in the medical field were more likely to use the caduceus.
 Modern political propaganda
Following the Christian context as a symbol for evil serpents are sometimes featured in political propaganda. They were used to represent Jews in antisemitic propaganda. Snakes were also used to represent the evil side of drugs in such films as Narcotic and Narcotics: Pit of Despair.
- Burston, Daniel: 1994, "Freud, the Serpent & The Sexual Enlightenment of Children", International Forum of Psychoanalysis, vol. 3, pp. 205-219
- Joseph Campbell, Occidental Mythology: the Masks of God, 1964: Ch. 1, "The Serpent's Bride."
- John Bathurst Deane, The Worship of the Serpent, 1833. (On-line text)
- David P. Chandler, A History of Cambodia, 1992.
- Lewis Richard Farnell, The Cults of the Greek States, 1896.
- Joseph Eddy Fontenrose, Python; a study of Delphic myth and its origins, 1959.
- Jane Ellen Harrison, Themis: A Study of the Social Origins of Greek Religion, 1912. cf. Chapter IX, p.329 especially, on the slaying of the Python.  
- Joseph Lewis Henderson and Maud Oakes, The Wisdom of the Serpent. The tribal initiation of the shaman, the archetype of the serpent, exemplifies the death of the self and a transcendent rebirth. Analytical psychology offers insights on the meaning of death symbolism and the serpent symbol.
- Edgar Allan Poe, The Cask of Amontillado, available in an online version at literature.org.
- Carl A. P. Ruck, Blaise Daniel Staples & Clark Heinrich, The Apples of Apollo: Pagan and Christian Mysteries of the Eucharist, 2001.