The Ideas

The caduceus

The caduceus is the herald’s staff of Hermes, the god the Romans called Mercury: a rod with two snakes twined around it, often topped by a pair of wings, and not the rod of Asclepius, the one-snake staff that ancient writers give the god of medicine. The two-snake staff reached medical badges by a route that can be dated step by step; the best-known step came in 1902, when the US Army put it on the uniforms of its medical officers.

Each step below is tied to the earliest source we could open, with edition and page. Where a popular story has no early source, the page says so. The method is the one behind Ask for the date: find when a claim is first written down, then see what later centuries added to it.

What the caduceus is

The word belongs to the herald. In Greek the staff is the kērykeion (κηρύκειον) and the herald is the kēryx. The Liddell-Scott-Jones lexicon defines kērykeion as “a herald’s wand” and records a proverb from the lexicon of Photius, τὸ κηρύκειον ἢ τὴν μάχαιραν, which it glosses “peace or the sword”. The wand marked a messenger who could pass between enemies. Thucydides shows what its absence meant: in the quarrel over Corcyra that came before the Peloponnesian War, the Corinthians sent men to the Athenians in a boat “without a herald’s wand”, as an experiment (1.53, tr. Crawley).

Hermes carries a wand in Homer, but there it is a wand of sleep and waking, held as he leads the dead. At the start of the last book of the Odyssey he calls up the spirits of the suitors: “He held in his hands his wand, a fair wand of gold, wherewith he lulls to sleep the eyes of whom he will, while others again he wakens even out of slumber” (24.1-4, tr. A. T. Murray, 1919).

The Homeric Hymn to Hermes says where the staff came from. After the young Hermes has given Apollo the lyre, Apollo swears friendship and promises: “I will give you a splendid staff of riches and wealth: it is of gold, with three branches, and will keep you scatheless” (lines 529-530, tr. Evelyn-White, 1914, p. 401). None of these texts mentions snakes. The snakes are plain in Greek objects, and the story that explains them is Roman.

The same scene explains the caduceus as a sign of trade. Just before the gift Apollo tells Hermes: “you have an office from Zeus, to establish deeds of barter amongst men throughout the fruitful earth” (lines 516-517, p. 401), and the staff he then promises is one “of riches and wealth”. Garrison still calls Mercury “the god of commerce and merchants” (1919, p. 14), and Hamann and Martelon (2016) list commerce among the meanings of the caduceus. Trade, like heralding, is one of Hermes’ own offices; medicine is not.

Where the snakes and the wings come from

The oldest Greek object checked for this page is the bronze head of a herald’s staff in the Metropolitan Museum of Art (1989.281.57), Greek, dated late 6th to early 5th century BCE and 18.7 cm high. Two crested snake heads face each other at the top; below them the bodies cross in a knot and close into a ring above the socket. It has no wings. On an Athenian oil flask of about 480-470 BCE attributed to the Tithonos Painter (Metropolitan Museum 25.78.2), Hermes runs with the staff in his hand, and the wings are on his boots.

The first written explanation of the two snakes that we found is in the Latin star book that has come down under the name of Hyginus, a work of the Roman imperial period. Under the constellation of the Lyre it tells how Mercury let Apollo claim the lyre as his invention and received from him a little staff (virgula) as a gift. Travelling to Arcadia, Mercury saw two snakes with their bodies joined, attacking each other; he put the staff between them, they parted, and he declared the staff a sign of peace. “Some, too, when they make caducei, make two snakes entwined on the staff, because for Mercury this had been the beginning of peace” (De astronomia 2.7, ed. Bunte, 1875, pp. 43-44; our translation).

Wings on the staff itself are older than any text that explains them. A silver denarius struck in Rome for the moneyer M. Plaetorius Cestianus, dated 69-57 BCE, shows a caduceus with wings spread on the staff (Harvard Art Museums 1976.79.1016). A meaning for every part, wings included, is spelled out in late antiquity. Macrobius, a Latin author of the early 5th century CE, writes in the Saturnalia that the Egyptians shaped the caduceus as two serpents, male and female, joined: the snakes are tied in the middle by the knot called Hercules’, their heads bend round into a circle and meet in a kiss, their tails run back to the handle, “and they are adorned with wings springing from the same part of the handle” (1.19.16, ed. Eyssenhardt, 1893, pp. 111-112; our translation). Macrobius uses the staff to show that the Sun is worshipped in Mercury, and says the Egyptians also read it as a figure of human birth: the kiss stands for love, the knot for necessity (1.19.17-18). That is a late Latin allegory, which its author credits to the Egyptians. No earlier source checked here says the snakes are male and female.

The other staff: Asclepius and his one snake

Ancient writers give medicine a different staff. In Ovid’s Metamorphoses (early 1st century CE) the god of healing appears in a dream to a Roman, “holding his rustic staff in his left hand”, and says: “Only look upon this serpent which twines about my staff” (15.654-659, tr. Miller, 1916, vol. II, pp. 410-411). One staff, one snake, no wings.

The Hyginus star book has a story for this snake too, under the constellation of the Snake-holder. Asclepius, shut away to think how he might heal Glaucus, was holding a staff (bacillum) when a snake crept up to it; he killed it. A second snake came with a herb in its mouth and laid it on the head of the first, and both went away; with the same herb Asclepius brought Glaucus back to life. “Led by this custom,” the passage ends, “his descendants handed down to the rest that physicians should use snakes” (De astronomia 2.14, ed. Bunte, pp. 51-52; our translation). Macrobius explains the snake beside the statues of Aesculapius and of Salus, Health, by the way snakes shed their old skin each year, as bodies recover their former strength (1.20.1-2, ed. Eyssenhardt, p. 112).

The World Health Organization follows the ancient division. Its emblem, “chosen by the First World Health Assembly in 1948”, is the United Nations symbol “surmounted by a staff with a snake coiling round it”, which WHO traces to Asclepius.

From Mercury’s staff to medical badges, dated

How the staff first came near medicine puzzled the medical historian Fielding H. Garrison, who wrote in 1919 as a lieutenant colonel of the Army Medical Corps. He listed early appearances of the caduceus beside medicine and admitted: “Why it should appear in this relation no one knows” (p. 14). The early uses we could check show why: each gave the two snakes a meaning other than healing.

Read down the third column. Of the uses we could check before 1902, none explains the two snakes as a sign of healing: Froben glossed them with the Gospel, Caius with good government, Maier with alchemy, and the Army regulation of 1857 with a rank. Caius is the closest case, a physician presiding over physicians, and he says plainly that his caduceus stands for the way the college should be ruled.

The Army’s own explanation, 1919

Garrison defended the choice. Of the hospital stewards’ chevrons he wrote: “There can be no question as to its use here. It was obviously employed to indicate that litter-bearers and Hospital Corps men are non-combatants” (p. 15). He knew the other staff well: the coat of arms of the Medical Corps “bears the Æsculapian staff with the single snake”, he noted, “but it is the caduceus which appears on the collar” (p. 15). His conclusion divided the work between them: the caduceus as a badge of neutrality for medical officers in the field, like the Red Cross, and the one-snake staff for the Corps’ medical functions (pp. 15-16).

Garrison’s dates do not all hold. He put the caduceus in “the heraldic devices of Sir William Butts, physician to Henry VIII, and the Swiss medical printer Froben” in “the late sixteenth century” (p. 14). Froben’s device is in print by February 1516, and Butts died on 22 November 1545, and the arms the Dictionary of National Biography (1886) gives him have no caduceus; we have not found the device Garrison meant. He dated Caius’s gift to his Cambridge college to 1556 and took 25 March 1558 for a later visit; Venn, from Caius’s own Annales, shows the emblems handed over on that day. Following Frothingham, he dated the Mesopotamian libation vase he took as the first caduceus to “about 3500 B.C.” (p. 13), a date discussed below. He dated the hospital stewards’ caduceus to 1856. The earliest regulation we have read that prescribes it is the edition dated 1 January 1857, and a date of 1851 is cited from William K. Emerson’s Encyclopedia of United States Army Insignia and Uniforms (1996), which we have not seen.

How the 1902 decision was made is told differently a century later. According to the ophthalmologist George Bohigian (2019), the proposal came from an assistant surgeon, Captain Frederick Reynolds; Surgeon General Sternberg turned it down, his successor Forwood approved it, and the “caduceus of gold” was adopted on 17 July 1902. Bohigian writes that Reynolds’s correspondence with the Surgeon General’s office shows “he was unaware of the distinction between the caduceus and Aesculapius”. That sentence carries no reference; for Sternberg, Forwood and the date he cites R. A. Wilcox and E. M. Whitham (2003). We have not seen the letters.

Mercury’s staff in Hermetic and alchemical books

Hermes Trismegistus, the author-figure of the Hermetic treatises, grew out of the Greek Hermes and the Egyptian Thoth, a fusion traced in who Hermes Trismegistus was. The treatises do not hand him the staff. A search of the scanned text of Walter Scott’s first volume (1924), which prints the Greek and Latin treatises with an English translation, finds no caduceus.

The Asclepius does something more telling: it names the two gods side by side and keeps them apart. Hermes Trismegistus tells his pupil about “your grandfather, Asclepius, who was the first inventor of the art of healing”, who has a temple in the Libyan mountain and still helps the sick, and then about “my grandfather Hermes, whose name I bear”, who dwells in the city named after him and helps those who come to him (ch. 37, tr. Scott, vol. I, p. 359). In the Hermetic dialogue, healing runs in the family of Asclepius, not of Hermes.

The alchemists did give Mercury his staff, as a sign of the “philosophical Mercury” of their art (on the art itself, see the Great Work). Michael Maier’s emblem book Atalanta fugiens (Oppenheim, 1618) takes the motto of its first emblem from the Emerald Tablet, “the wind carried it in its belly” (the Tablet clause by clause). The discourse on that emblem says Mercury, “because he carries a caduceus girded crosswise with two serpents, who leads souls out of bodies and back, and works many such contraries, best expresses the symbol of the philosophical Mercury” (Discourse I, p. 15; our translation). In Discourse XXV the chemists’ dragons are allegory, not real animals: the dragon always stands for Mercury, “hence Mercury is to be seen with a double serpent joined in the caduceus”, and the ancients, as makers of hieroglyphs, joined the dragon to Aesculapius too (p. 110; our translation). For Maier the snakes of both gods are signs in the chemical work. Neither is the badge of a profession.

Ibis checks: the caduceus

What the sources attest, claim by claim, with the earliest source we could check.

What is disputed

A Mesopotamian origin. In 1916 the archaeologist A. L. Frothingham argued that Hermes descends from a Babylonian snake god and the caduceus from Babylonian images of the god Ningishzida. His first example is a green steatite libation vase from Telloh (Lagash), now in the Louvre, dedicated by Gudea, ruler of Lagash, to Ningishzida: at its centre two snakes face each other at the top of a staff, their tails interlaced at the base (pp. 181-182). Garrison took this as settled and, as Frothingham had reckoned Gudea’s time (p. 183), dated the vase “about 3500 B.C.”; the Metropolitan Museum dates its statue of Gudea (59.2) to about 2090 BCE. The image is real. The link from it to the Greek herald’s staff is Frothingham’s argument, and we have found no ancient source that makes it.

Mistake or choice. Garrison (1919) presented the 1902 insignia as a deliberate badge of non-combatants. Claus Hamann and MaryKate Martelon (2016) speak of “the US error”, and Bohigian (2019) of a misunderstanding by the officer who proposed it. The 1857 regulation adds one fact to the argument: the Army had chosen the caduceus for its hospital stewards long before 1902. The regulation gives no reason, and Garrison’s “obviously” is his reading, written 62 years later.

How common it is now. A book-length history of the symbol is Walter J. Friedlander’s The Golden Wand of Medicine (1992). Percentages from its survey of organisations circulate widely; Hamann and Martelon quote one, that “76% of commercial organizations were more likely to use the caduceus”, and say they could not test it. We have not seen the book’s table, so we give no figures from it. Their own count (2013-2015) is checkable: among current and past emblems of 482 schools of medicine and the health professions in the US, Puerto Rico and Canada, 205 showed some form of the staff of Asclepius, 25 some form of the caduceus, and 249 neither.

For other symbols that arrive with an ancient pedigree, Is it really ancient? sorts a claim into dated layers the same way.

Key facts

Name	Greek kērykeion, “a herald’s wand” (Liddell-Scott-Jones); Latin caduceus
Owner	Hermes, the Roman Mercury: herald of the gods and guide of souls, whom Zeus also charged with barter among men (Homeric Hymn to Hermes 516-517)
Form	Staff with two snakes; wings on the staff on a Roman denarius of 69-57 BCE, explained by Macrobius (early 5th century CE)
Oldest Greek object checked	Greek bronze staff head with two snakes, late 6th-early 5th century BCE (Metropolitan Museum 1989.281.57)
Why two snakes	Hyginus, De astronomia 2.7: Mercury parts two fighting snakes, a sign of peace
Medicine’s staff	Rod of Asclepius: one snake, no wings (Ovid, Metamorphoses 15.654-659)
US Army	Hospital stewards’ chevrons by 1857 (par. 1400); medical officers’ uniforms from 1902
WHO emblem	Staff with one snake, chosen by the First World Health Assembly in 1948

Fair questions

What is the difference between the caduceus and the rod of Asclepius?

The caduceus is the herald’s staff of Hermes, the Roman Mercury: two snakes, often with wings at the top. The rod of Asclepius is a plain staff with one snake and no wings, the attribute of the god of healing (Ovid, Metamorphoses 15.654-659; Hyginus, De astronomia 2.14). The World Health Organization chose the one-snake staff for its emblem in 1948.

Why does the caduceus have two snakes?

The earliest written explanation we found is Roman: in the De astronomia under Hyginus’ name (2.7), Mercury puts his staff between two fighting snakes, they part, and the staff becomes a sign of peace. Greek bronze staff heads with two facing snakes are older, from the late 6th or early 5th century BCE (Metropolitan Museum 1989.281.57). Macrobius, in the early 5th century CE, adds that the snakes are male and female.

Why is the caduceus used as a medical symbol?

Mainly through the US Army: its regulations of 1857 put a caduceus on the half chevrons of hospital stewards (par. 1400), and in 1902 it appeared on the uniforms of medical officers. Fielding Garrison explained in 1919 that it marked non-combatants, while the Medical Corps’ coat of arms carried the one-snake staff. Earlier uses near medicine meant something else: John Caius’s silver caduceus at the College of Physicians (first used in January 1557, Old Style) stood, by his own account, for mild and prudent rule, not for healing.

Is the caduceus a Hermetic symbol?

Not in the Hermetic treatises: a search of Walter Scott’s text (1924) finds no caduceus, and the Asclepius (ch. 37) gives the invention of healing to an elder Asclepius, the pupil’s grandfather, not to Hermes. The alchemists did use it: Michael Maier’s Atalanta fugiens (1618) says Mercury, because he carries a caduceus girded with two serpents, best expresses the symbol of the “philosophical Mercury” (p. 15).

Which symbol is correct for medicine?

By the ancient sources, the rod of Asclepius: one snake, no wings. The caduceus belongs to Hermes as herald and, in Roman sources, stands for peace. The two-snake staff is still in medical use: in a survey made between November 2013 and January 2015, 25 of 482 health schools in the US, Puerto Rico and Canada showed a form of the caduceus on current or past emblems, against 205 with a form of the staff of Asclepius (Hamann and Martelon 2016).

Sources & further reading

• F. H. Garrison, “The Use of the Caduceus in the Insignia of the Army Medical Officer”, Bulletin of the Medical Library Association 9.2 (October 1919), pp. 13-16; PubMed Central, PMC234831 and Internet Archive scan (consulted 31 October 2026). On Sir William Butts: Charles Trice Martin, “Butts, Sir William”, in Leslie Stephen (ed.), Dictionary of National Biography, vol. 8 (London: Smith, Elder, 1886), pp. 103-104; Internet Archive scan (consulted 1 November 2026).
• Hugh G. Evelyn-White (tr.), Hesiod, the Homeric Hymns and Homerica, Loeb Classical Library (London: Heinemann; New York: Macmillan, 1914), Homeric Hymn IV, To Hermes, lines 529-530, p. 401; Internet Archive scan (consulted 31 October 2026).
• Homer, Odyssey 24.1-4, tr. A. T. Murray, Loeb Classical Library (London: Heinemann; Cambridge, MA: Harvard University Press, 1919), at the Perseus Digital Library (consulted 31 October 2026).
• H. G. Liddell, R. Scott and H. S. Jones, A Greek-English Lexicon, s.v. κηρύκειον (“a herald’s wand”, citing Herodotus 9.100 and Thucydides 1.53; the proverb from Photius), at lsj.gr; Thucydides 1.53 in Richard Crawley’s translation, Project Gutenberg (both consulted 31 October 2026).
• Hyginus, De astronomia 2.7 and 2.14: Bernhard Bunte (ed.), Hygini Astronomica (Leipzig: T. O. Weigel, 1875), pp. 43-44 and 51-52; Internet Archive scan (consulted 31 October 2026).
• Ovid, Metamorphoses 15.654-659: Frank Justus Miller (tr.), Metamorphoses, vol. II, Loeb Classical Library (London: Heinemann, 1916), pp. 410-411; Internet Archive scan (consulted 31 October 2026).
• Macrobius, Saturnalia 1.19.16-18 and 1.20.1-2: Franz Eyssenhardt (ed.), Macrobius, 2nd ed. (Leipzig: Teubner, 1893), pp. 111-112; Internet Archive scan (consulted 31 October 2026). On the author’s date: Alan Cameron, “The Date and Identity of Macrobius”, Journal of Roman Studies 56 (1966), pp. 25-38, doi:10.2307/300131.
• The Metropolitan Museum of Art, New York: bronze finial of a kerykeion (herald’s staff), Greek, late 6th-early 5th century BCE, 1989.281.57; terracotta lekythos attributed to the Tithonos Painter, Attic, about 480-470 BCE, 25.78.2; statue of Gudea, Neo-Sumerian, about 2090 BCE, 59.2 (records and public-domain images consulted through the museum’s open-access collection data, 31 October 2026). Harvard Art Museums, Cambridge, MA: denarius of M. Plaetorius M.f. Cestianus, Rome, 69-57 BCE, RRC 405/5, 1976.79.1016 (record and photograph consulted 1 November 2026).
• A. L. Frothingham, “Babylonian Origin of Hermes the Snake-God, and of the Caduceus I”, American Journal of Archaeology 20.2 (1916), pp. 175-211 (Gudea’s vase and its date, pp. 181-183); Internet Archive scan (consulted 31 October 2026).
• Erasmus (ed.), Novum Instrumentum omne (Basel: Johann Froben, February 1516), colophon with Froben’s device, Universitätsbibliothek Basel, BibG B 3; e-rara, doi:10.3931/e-rara-2849, scan page [991] (consulted 31 October 2026).
• E. S. Roberts (ed.), The Works of John Caius, M.D., with a memoir by John Venn (Cambridge: University Press, 1912): Venn’s memoir, pp. 18-19; Caius, Annales Collegii Medicorum, p. 42; Internet Archive scan (consulted 31 October 2026).
• War Department, Regulations for the Army of the United States, 1857 (New York: Harper & Brothers, 1857), par. 1400, pp. 439-440; Internet Archive scan of the National Library of Medicine copy (consulted 31 October 2026). The date 1851 for the hospital stewards’ badge is cited from William K. Emerson, Encyclopedia of United States Army Insignia and Uniforms (Norman: University of Oklahoma Press, 1996), which we have not seen.
• George Bohigian, “The Caduceus vs. Staff of Aesculapius: One Snake or Two?”, Missouri Medicine 116.6 (2019), pp. 476-477; PubMed Central, PMC6913859 (consulted 31 October 2026); for the Army’s 1902 decision it cites R. A. Wilcox and E. M. Whitham, “The Symbol of Modern Medicine: Why One Snake Is More Than Two”, Annals of Internal Medicine 138.8 (2003), pp. 673-677, which we have not seen.
• Claus Hamann and MaryKate Martelon, “Branding Asklepios and the Traditional and Variant Serpent Symbol Display Among Health Professional Schools in the United States, Puerto Rico, and Canada: A Cross-Sectional Survey”, JMIR Medical Education 2.1 (2016), e6, doi:10.2196/mededu.5515; it cites Walter J. Friedlander, The Golden Wand of Medicine: A History of the Caduceus Symbol in Medicine (New York: Greenwood Press, 1992), which we have not seen.
• World Health Organization, “The WHO logo and emblem” (consulted 31 October 2026).
• Walter Scott (ed. and tr.), Hermetica, vol. I (Oxford: Clarendon Press, 1924), Asclepius III.37, p. 359; Internet Archive scan. Michael Maier, Atalanta fugiens (Oppenheim: Hieronymus Galler for Johann Theodor de Bry, 1618), Emblem I and Discourses I and XXV, pp. 15 and 110; Internet Archive scan of the Getty Research Institute copy (both consulted 31 October 2026).