The two-snake medical symbol really belongs to the god of merchants
Many American ambulances and clinics display a winged staff wrapped by two snakes. That emblem is the caduceus, the wand of Hermes, patron of trade, travellers and smooth talkers. The true ancient sign of medicine is the rod of Asclepius, with one snake and no wings; the mix-up owes much to a single Army officer in 1902.
In Greek myth the caduceus was a herald's staff, carried by Hermes and by other divine messengers such as Iris. One story says Apollo gave it to Hermes in thanks for the lyre Hermes had made from a tortoise shell. Another has Hermes separating two fighting serpents with his wand, making it an emblem of peace, and Roman envoys negotiating truces carried one for protection. It was said to wake sleepers, lull the wakeful and ease the dying.
The image may be far older than Greece. Staffs twined with two snakes appear on Mesopotamian seals and were a symbol of the Sumerian god Ningishzida, possibly dating to 4000 to 3000 BC, and some scholars read the design as mating snakes. It also turns up on coins of India's Maurya Empire, perhaps as the personal mark of King Ashoka. In later antiquity a stylised version became the astronomical sign for the planet Mercury.
Through Mercury's links with commerce and eloquence, the staff came to stand for trade, rhetoric and even printing; several early printers used it as their mark. So did a London publisher of medical books in the 1830s, which may have nudged it towards medicine. The decisive step came when the US Army Medical Corps adopted it as insignia in 1902 at the urging of one officer, though records disagree about which one.
The confusion persists along revealing lines. One survey found that 62% of professional healthcare associations in the US use the rod of Asclepius, while 76% of commercial health organisations use the caduceus; the author suggested that businesses care more about visual appeal than history. One critic writing in Scientific Monthly scoffed that Hermes' emblem suited salesmen and quacks, and would look more fitting on a hearse, since Hermes also guided the dead.
Source: Caduceus
