Aesculapius, the mythological god of medicine, carried a knotty wooden staff entwined with a single snake representing life-giving powers. The two-snake design dates back some 4,000 years to Babylon. It reappeared in Greek mythology with a pair of wings added, as Hermes’ wand, and called the Caduceus, a name derived from the Greek word meaning herald’s wand or staff.
Symbol Sourcebook by Henry Dreyfuss, 1972.
Vesalius was not fond of the Aesculapius, seeing it as a symbol of the antiquated devotion to Galen. It still remained a symbol of medicine despite his denouncement.