Amphisbaena

Origin

The earliest unambiguous reference is in the Theriaca of Nicander of Colophon (second century BCE), a Greek didactic poem on venomous animals. The mythological origin is fixed by the Roman poet Lucan in his Pharsalia IX.708-728 (c. 65 CE), where Cato's army marches through Libya and encounters the Amphisbaena among the serpents born from Medusa's blood: Dipsas, Seps, Aspis, and the two-headed Amphisbaena. Pliny the Elder Natural History VIII.35, Aelian De natura animalium IX.23, Silius Italicus Punica III.317-318, and Isidore of Seville's Etymologies XII.4.20 (seventh century CE) consolidated the description, which became standard in the medieval bestiaries, especially the Aberdeen Bestiary and MS Bodley 764 of the twelfth and thirteenth centuries.

Features

• Two heads, one at each end of the body
• Able to move forward in either direction
• One head sleeps while the other watches, never wholly defenceless
• Born from the blood of Medusa in the Libyan desert
• Venomous from both heads
• Cold-resistant; said by Pliny to move even in deep winter

Stories

Ancient medicine adopted the Amphisbaena as a talisman. Pliny Natural History XXX states that a pregnant woman who wears a living Amphisbaena will not miscarry, and that wrapping its skin around a walking-stick wards off cold. In medieval heraldry it appears on the 1372 tomb brass of William de Buslingthorpe in Northamptonshire and in seventeenth- and eighteenth-century armorial manuals. Dante invokes it in Inferno canto XXV, the metamorphosis of the thieves, and Milton in Paradise Lost X.524 names it among the writhing serpents into which Satan and his followers are transformed. It reappears in Jorge Luis Borges's Book of Imaginary Beings (1957) and is a canonical entry in Dungeons and Dragons monster manuals.

Weakness

Ancient sources rarely specify a predator. Later tradition holds that, since the Amphisbaena was born of Medusa's blood, divine weapons such as the harpe of Perseus retain power over it. Renaissance allegory mocks the creature for paralysis when both heads try to go the same direction at once, the two minds interfering with each other. Modern zoology since the 1960s has identified the mythical description as a misreading of the burrowing reptiles of the family Amphisbaenidae, whose blunt tail resembles their head and which can reverse direction in their tunnels: less a mythic vulnerability than a natural-history misunderstanding.

Cultural Significance

The Amphisbaena is no mere serpent but an emblem of duality. Medieval bestiaries read it as the divided soul, hypocrisy, the sin of the double mind. In heraldry the two heads stand for vigilance and prudence at all sides. Dante uses it for thieves and traitors, Milton for the metamorphosis of fallen angels, and Borges, recapitulating the tradition, calls it 'the snake of two faces of the soul'. In modern zoology, Carl Linnaeus in his Systema Naturae of 1758 named a genus of burrowing reptiles Amphisbaena, fixing the mythic name in scientific taxonomy. The motif also survives in pop culture, from Dungeons and Dragons through Borges's twentieth-century re-canonisation to the heraldic crest of several modern institutions.

In Popular Culture

Nicander of Colophon, Theriaca (2nd c. BCE) — earliest unambiguous referenceLucan, Pharsalia IX.708-728 (c. 65 CE) — born of Medusa's blood in the Libyan desertPliny the Elder, Natural History VIII.35 — 'the only serpent with two heads'Aelian, De natura animalium IX.23 and Silius Italicus, Punica III.317-318Isidore of Seville, Etymologies XII.4.20 (7th c. CE) — standard medieval bestiary entryDante, Inferno XXV and John Milton, Paradise Lost X.524Jorge Luis Borges, Book of Imaginary Beings (1957) — twentieth-century re-canonisation