Caduceus: A staff with two snakes entwined about it, topped by a pair of wings. The caduceus was carried by the Greek messenger god Hermes, whose Roman counterpart was Mercury, and is therefore the sign of a herald. By a curious misconception, the caduceus also became the insignia of the US Army Medical Corps and a well-known symbol of physicians and medicine. The Corps should have chosen the symbol of medicine: the rod of Aesculapius, which has only one snake and no wings. No wings were necessary because the essence of medicine was not speed. The single serpent that could shed its skin and emerge in full vigor represented the renewal of youth and health.