Caduceus

The caduceus (☤; /kəˈdjuːʃəs, -siəs/; from Latin cādūceus, from Ancient Greek κηρύκειον (kērúkeion) 'herald's wand, staff') is the staff carried by Hermes in Greek mythology and consequently by Hermes Trismegistus in Greco-Egyptian mythology. The same staff was borne by other heralds like Iris, the messenger of Hera. The short staff is entwined by two serpents, sometimes surmounted by wings. In Roman iconography, it was depicted being carried in the left hand of Mercury, the messenger of the gods.

Some accounts assert that the oldest imagery of the caduceus is rooted in Mesopotamia with the Sumerian god Ningishzida; his symbol, a staff with two snakes intertwined around it, dates back to 4000 BC to 3000 BC. This iconography may have been a representation of two snakes copulating.

As a symbol, 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 astronomical symbol for planet Mercury. Thus, through its use in astrology, alchemy, and astronomy it has come to denote the planet Mercury and by extension the eponymous planetary metal. It is said that the wand would wake the sleeping and send the awake to sleep. If applied to the dying, their death was gentle; if applied to the dead, they returned to life.

By extension of its association with Mercury and Hermes, the caduceus is also a symbol of commerce and negotiation, two realms in which exchange balanced by reciprocity is recognized as an ideal. This association is ancient, and consistent from classical antiquity to modernity. The caduceus is also a symbol of printing, by extension of the attributes of Mercury associated with writing and eloquence.

Although the Rod of Asclepius, which has only one snake and no wings, is the traditional and more widely used symbol of medicine, the caduceus is sometimes used by healthcare organizations. Given that the caduceus is primarily a symbol of commerce and other non-medical symbology, many healthcare professionals disapprove of this use.

The Homeric Hymn to Hermes relates how his half brother Apollo was enchanted by Hermes's music from his lyre fashioned from a tortoise shell, which Hermes kindly gave to him. 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.