Caduceus

Froben’s printer’s mark

The Basel printer Johann Froben, publisher of Erasmus, used a caduceus as his printer’s mark from 1515, according to the ETH Zurich library. Printers’ marks identified the printer of a book and acted as a kind of copyright. Froben’s, designed by Hans Holbein the Younger, shows two hands holding a staff, two snakes winding up it and a dove enthroned on top, after Christ’s words in Matthew’s Gospel: “Be ye therefore wise as serpents, and harmless as doves.” The ETH library notes that Froben printed Erasmus’s Greek and Latin New Testament, and that for the ancient Greeks the caduceus stood for commerce. Tyson, following an earlier writer, called Froben’s device the earliest instance of the caduceus being taken for a medical sign, but saw no reason to think Froben meant it for either Asclepius or Hermes: he had made up his own symbolism.

How it came into medicine

Tyson traced a line of physicians who used it after Froben. Sir William Butts, physician to Henry VIII, used it, and the physician John Caius gave a silver caduceus to Gonville and Caius College. Then, Tyson wrote, nothing more is heard of it until 1844, when it appeared on the title pages of a London medical publisher, Churchill. Friedlander reads the history the same way: in the sixteenth and seventeenth centuries the caduceus stood for wise and eloquent people, some of them physicians, and the nineteenth-century publisher took it up as a sign that he was a commercial deliverer of information, not that his books were medical.

In the United States it came in through the Army. The Army’s Institute of Heraldry quotes an 1851 regulation putting “a caduceus embroidered in yellow silk” on the chevrons of the Medical Department’s hospital stewards; the National Museum of Civil War Medicine dates the stewards’ caduceus to 1856, and says it marked them and the stretcher bearers as non-combatants. The US Public Health Service adopted it in 1871, according to the museum. In 1902 it became the insignia of the Army’s medical officers and enlisted men alike. Friedlander’s account is that the First World War made the sign widely known, and that once popular, it “bred popularity”.

Why is the caduceus used for medicine?

Because the US Army chose it for its Medical Department in 1902, and American medicine followed. Why the Army chose it is disputed. Writing in the Army Medical Department’s history newsletter, the insignia historian William K. Emerson says that Colonel John Van Rensselaer Hoff, the medical member of the 1902 uniform board, proposed it as the emblem ancient merchant ships had flown to mark themselves as non-combatants, a sign of neutrality; Hoff had ruled out the Geneva cross because it was also the emblem of Switzerland. The National Museum of Civil War Medicine says no explanation for the choice was ever given, and that it is thought to have been meant to mark the corps as non-combatants rather than to stand for medicine. The Institute of Heraldry’s present description of the branch insignia says the caduceus symbolises knowledge, wisdom, promptness and medical skill. The Army’s regimental insignia for the same corps still carries the one-snake staff, from a device of about 1818.

Was it a mistake?

Its critics say so. Tyson, in The Scientific Monthly in 1932, called it “an incontrovertible fact” that the wand with two snakes belongs to Hermes, not Asclepius, and judged Hermes’s relationship to medicine “tolerably near absolute zero”. Schwamm, writing in 2013, set the two emblems against each other: the rod for the art of healing, the caduceus of the god of commerce for medicine’s commercial side, and he cited a 1990 survey in which commercial organizations were the likeliest to use it. Others defend it on its own history. When the National Museum of Civil War Medicine chose a logo in 2020, the choice between the two snakes caused the most heated debate of the redesign; the museum concluded that either would have been on solid historical ground and took the caduceus, because Civil War hospital stewards and stretcher bearers wore it.

Often confused with the rod of Asclepius

Count the snakes. The caduceus has two, and two outstretched wings at the top; the rod of Asclepius has one snake on a plain staff and no wings. Gonville and Caius College makes the same point about its own caduceus: John Caius was a doctor, but the snakes on the college’s staff are those of Hermes, and it stands for negotiation and eloquence.

Where you’ll see it

At Gonville and Caius College, Cambridge, the silver caduceus that John Caius gave when he refounded the college in 1557 is handed to each new Master “as a symbol of prudent government”. Caius himself, the college’s President said at the 2018 installation, wrote that its silver stands for gentleness of government and its four serpents for wise government. In occult art, Éliphas Lévi’s nineteenth-century figure of Baphomet has a caduceus in place of the genitals, which Lévi read as eternal life. In A. E. Waite’s tarot, the caduceus of Hermes rises above the cups on the Two of Cups, with a lion’s head between its wings.