Two types of caduceus are confused in modern iconography. The symbol which uses a single snake entwined about a bough is the correct one when used in reference to the medical profession. It is the sole symbol of the AMA and other medical groups.
This single snake adorned the staff of Aesculapius (Roman) or Asklepios (Greek) who was a famous human physician circa 1200 BCE who was later worshipped as a god. (According to some versions he was the son of Apollo, tutored in surgery by a centaur, a ‘monster’ having the head, trunk and arms of a man and the body and legs of a horse). Whichever, there were temples erected to him in ancient Greece. This god or man of healing was often pictured/depicted with a rearing snake at his feet, and by 200 BCE his snake-laden wand represented medicine. Amongst the temples at Epidaurus the ancient Greek school of medicine grew. The sick came to sleep in the temples, hoping to be cured or granted a vision of the cure. Over the years the priests observed the ill people and learned the art of diagnosis.
Sir William Butts, physician to King Henry VIII, was granted the caduceus as this crest. This was permitted because it had also become “symbol of military heralds seeking to negotiate peace with an enemy; the physician’s enemy being disease. In 1856 the U.S. Marine Health Service, the predecessor of today” Public Health Service, made a two-snake caduceus its symbol. Accompanied by an anchor, it remains the PHS symbol today. In 1902, it was adopted by the Army Medical Corps.” The Army Medical Corps version consists of a staff with two formal wings at top in addition to the two entwined serpents. This staff is not regarded as a medical emblem but as an administrative emblem, implying neutrality.
The two-snake depiction is the symbol of Mercury (Roman) or Hermes (Greek), the winged messenger of the gods. Its was originally an olive branch with green twigs (eventually becoming ribbons) wound around it. According to myth, Hermes once saw two snakes fighting. He hurled his staff between them, whereupon they wound about it and became friends. However, this myth may have evolved because of confusion with the staff’s streamers. This versatile and busy god was also considered the god of commerce, protector of thieves and guide of departing souls to Hades.
Nevertheless, dispite its shrouded and mysterious origin, the single-snake staff is, according to the American College of Surgeons, “the symbol of choice by scholars and those in the medical profession, representing ‘the power and mystery of the healing art’.”
Text taken verbatim from “Yasgur’s Homeopathic Dictionary and Holistic Health Reference”, Jay Yasgur, 4th ed.