As a symbolic object it represents Hermes (or the Roman Mercury), and by extension trades, occupations or undertakings associated with the god. In later Antiquity the caduceus provided the basis for the astrological symbol representing the planet Mercury . Thus, through its use in astrology and alchemy , it has come to denote the elemental metal of the same name.

By extension of its association with Mercury/Hermes, the caduceus is also a recognized symbol of commerce and negotiation, two realms in which balanced exchange and reciprocity are recognized as ideals. This association is ancient, and consistent from the Classical period to modern times. The caduceus is also used as a symbol representing printing, again by extension of the attributes of Mercury (in this case associated with writing and eloquence).

The caduceus is sometimes mistakenly used as a symbol of medicine and/or medical practice , especially in North America , because of widespread confusion with the traditional medical symbol, the rod of Asclepius , which has only a single snake and no wings.

The term kerukeion denoted any herald's staff, not necessarily associated with Hermes in particular.

Lewis Richard Farnell (1909) in his study of the cult of Hermes assumed that the two snakes had simply developed out of ornaments of the shepherd's crook used by heralds as their staff. This view has been rejected by later authors pointing to parallel iconography in the Ancient Near East. It has been argued that the staff or wand entwined by two snakes was itself representing a god in the pre-anthropomorphic era. Like the herm or priapus , it would thus be a predecessor of the anthropomorphic Hermes of the classical era.

Ancient Near East

William Hayes Ward (1910) discovered that symbols similar to the classical caduceus sometimes appeared on Mesopotamian cylinder seals . He suggested the symbol originated some time between 3000 and 4000 BCE, and that it might have been the source of the Greek caduceus.^[10] A.L. Frothingham incorporated Dr. Ward's research into his own work, published in 1916, in which he suggested that the prototype of Hermes was an "Oriental deity of Babylonian extraction" represented in his earliest form as a snake god. From this perspective, the caduceus was originally representative of Hermes himself, in his early form as the Underworld god Ningishzida , "messenger" of the "Earth Mother". The caduceus is mentioned in passing by Walter Burkert ^[12] as "really the image of copulating snakes taken over from Ancient Near Eastern tradition".

In Egyptian iconography, the Djed pillar is depicted as containing a snake in a frieze of the Dendera Temple complex .

The rod of Moses and the brazen serpent are frequently compared to the caduceus, especially as Moses is acting as a messenger of God to the Pharaoh at the point in the narrative where he changes his staff into a serpent.^[13]

Classical antiquity

Mythology

The Homeric hymn  to Hermes relates how Hermes offered his lyre fashioned from a tortoise shell as compensation for the cattle he stole from his half brother Apollo . Apollo in return gave Hermes the caduceus as a gesture of friendship. The association with the serpent thus connects Hermes to Apollo , as later the serpent was associated with Asclepius , the "son of Apollo". The association of Apollo with the serpent is a continuation of the older Indo-European dragon -slayer motif. Wilhelm Heinrich Roscher  (1913) pointed out that the serpent as an attribute of both Hermes and Asclepius is a variant of the "pre-historic semi-chthonic serpent hero known at Delphi as Python ", who in classical mythology is slain by Apollo.

One Greek myth of origin of the caduceus is part of the story of Tiresias , who found two snakes copulating and killed the female with his staff. Tiresias was immediately turned into a woman, and so remained until he was able to repeat the act with the male snake seven years later. This staff later came into the possession of the god Hermes, along with its transformative powers.

Another myth suggests that Hermes (or Mercury) saw two serpents entwined in mortal combat. Separating them with his wand he brought about peace between them, and as a result the wand with two serpents came to be seen as a sign of peace.

In Rome, Livy refers to the caduceator who negotiated peace arrangements under the diplomatic protection of the caduceus he carried.

Iconography

In some vase paintings ancient depictions of the Greek kerukeion are somewhat different from the commonly seen modern representation. These representations feature the two snakes atop the staff (or rod), crossed to create a circle with the heads of the snakes resembling horns. This old graphic form, with an additional crossbar to the staff, seems to have provided the basis for the graphical sign of Mercury (☿) used in Greek astrology  from Late Antiquity.

Use in alchemy and occultism

As the symbol of both the planet and the metal named for Mercury, the caduceus became an important symbol in alchemy .

The crucified serpent was also revived as an alchemical symbol for fixatio , and John Donne  (Sermons 10:190) uses "crucified Serpent" as a title of Jesus Christ .

Symbol of commerce

A simplified variant of the caduceus is to be found in dictionaries, indicating a “commercial term” entirely in keeping with the association of Hermes with commerce. In this form the staff is often depicted with two winglets attached and the snakes are omitted (or reduced to a small ring in the middle). The Customs Service of the former German Democratic Republic employed the caduceus, bringing its implied associations with thresholds, translators, and commerce, in the service medals they issued their staff.

Misuse as symbol of medicine

It is relatively common, especially in the United States, to find the caduceus, with its two snakes and wings, used as a symbol of medicine instead of the correct rod of Asclepius, with only a single snake. This usage is erroneous, popularised largely as a result of the adoption of the caduceus as its insignia by the US Army medical corps in 1902 at the insistence of a single officer (though there are conflicting claims as to whether this was Capt. Frederick P. Reynolds or Col. John R. van Hoff).

The rod of Asclepius is the dominant symbol for professional healthcare associations in the United States. One survey found that 62% of professional healthcare associations used the rod of Asclepius as their symbol. The same survey found that 76% of commercial healthcare organizations used the Caduceus symbol. The author of the study suggests the difference exists because professional associations are more likely to have a real understanding of the two symbols, whereas commercial organizations are more likely to be concerned with the visual impact a symbol will have in selling their products.

The initial errors leading to its adoption and the continuing confusion it generates are well known to medical historians. The long-standing and abundantly attested historical associations of the caduceus with commerce, theft, deception, and death are considered by many to be inappropriate in a symbol used by those engaged in the healing arts. This has occasioned significant criticism of the use of the caduceus in a medical context.

In Roman mythology , Felicitas (meaning "good luck" or "fortune") was the goddess or personification of good luck and success. The word felicitas, "luck", is also the source of the word and name felicity. She played an important role in Rome's state religion during the empire , and was frequently portrayed on coins . She became a prominent symbol of the wealth and prosperity of the Roman Empire .

Felicitas was unknown before the mid-2nd century BC, when a temple was dedicated to her in the Velabrum in the Campus Martius by Lucius Licinius Lucullus , using booty from his 151–150 BC campaign in Spain. The temple was destroyed by a fire during the reign of Claudius and was never rebuilt.

Another temple in Rome was planned by Julius Caesar and was erected after his death by Marcus Aemilius Lepidus on the site of the Curia Hostilia , which had been restored by Lucius Cornelius Sulla but demolished by Caesar in 44 BC. This temple no longer existed by the time of Hadrian , and its site probably lies under the church of Santi Martina e Luca .