Caduceus

A caduceus (kerykeion in Greek is a (sometimes) winged staff with two snakes wrapped around it. It was an ancient astrological symbol of commerce and is associated with the Greek god Hermes, the messenger for the gods, conductor of the dead and protector of merchants and thieves. It was originally a  herald's staff, sometimes with wings, with two white ribbons attached. The ribbons eventually evolved into snakes. The caduceus is sometimes inaccurately used as a symbol for medicine, especially in North America, but the traditional medical symbol is the rod of Asclepius with only a single snake and no wings.

Origin
The caduceus is strongly linked to the Greek god Hermes (Mercury in Roman mythology). The origin of the staff is described in the story of Tiresias, who found two snakes copulating and attempted to separate them with his staff. Tiresias was immediately turned into a woman, and so remained until he was able to repeat the act seven years later. This staff later came in to the possession of the god Hermes, along with its transformative powers.

Variations
In some cases, ancient depictions of the Greek kerykeion (e.g. on vase paintings) can be radically different from the modern representation (as in the picture at top right). These representations feature the two snakes atop the staff (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, has become the typographical Mercury-sign widely used in astrological and alchemistic contexts for centuries. Another simplified variant of the caduceus is to be found in dictionaries, indicating “commercial term”: the staff with two winglets attached, the snakes omitted (or better: reduced to a small ring in the middle).

Meaning
The caduceus is used by a variety of professions who have a connection with Hermes, who was the god of commerce, eloquence, invention, travel and theft. Examples of groups who use the caduceus include:
 * Merchants – The most recognised use of the caduceus is by merchants
 * Journalists – The symbol is often used by journalists, as Hermes was both a messenger and god of eloquence
 * Postal workers – Related to Hermes' role as a messenger.

Confusion with the rod of Asclepius
The caduceus is sometimes used as a symbol for medicine or doctors (instead of the rod of Asclepius) even though this is historically incorrect. A 1992 survey of American health organisations found that 62% of professional associations used the rod of Asclepius, whereas in commercial organisations, 76% used the caduceus.

Early confusion between the symbols almost certainly arose due to the links between alchemy and Hermes, whose symbol is the caduceus. The alchemists adopted the caduceus because Hermes, the God of Messengers, was also the patron lord of gamblers, thieves, tricksters and alchemists. By the end of the 16th century, alchemy became widely associated with medicine in some areas, leading to some use of the caduceus as a medical symbol.

The main reason for the modern confusion over the symbols occurred when the caduceus was adopted by the Medical Department of the United States Army in 1902. This was brought about by one Captain Reynolds, who after having the idea rejected several times by the Surgeon General, persuaded the new incumbent (WH Forwood) to adopt it. The inconsistency was noticed several years later by the librarian to the surgeon general, but was not changed.

There was further confusion caused by the use of the caduceus as a printer's mark (as Hermes was the god of eloquence and messengers), which appeared in many medical textbooks as a printing mark, although subsequently mistaken for a medical symbol.

Examples of usage

 * The caduceus is the official magazine of the Kappa Sigma Fraternity. The symbol (with a slight difference) appears on the Order's pledge pin and crest.
 * Caduceus Capital, a famous group of on & off-shore Venture Capital funds specializing in early-stage Life Science & Biotech security investments.
 * Columbia Business School uses a logo derived from the caduceus symbol. They also have other references to the Greek god Hermes including an alumni magazine.
 * The caduceus is used in the coat of arms of the Ukrainian city of Kharkiv.
 * The Renaissance artist Jacopo de' Barbari signed most of his work just with a (wingless) caduceus.

Medical uses

 * The caduceus is the official emblem of the United States Navy Hospital Corps. (see Hospital Corpsman)
 * A stylized caduceus was used on the outside of the main Starfleet Medical headquarters, in the Star Trek: Voyager episode "Endgame".

Standard representation
There are three Unicode representations of the caduceus: U+2624 on the Miscellaneous Symbols table, U+263F (the astrological form) and U+269A (the lexicographical form), both in the same range.