Protective iron: nails, horseshoes and touching iron
From the nail driven into the temple of Jupiter to the legend of Saint Dunstan and cold iron against fairies: iron in European protective beliefs.
Iron is the most common of the protective metals, and perhaps for that very reason one of the most present in popular belief. In many regions of Europe people touched an iron object to ward off bad luck, nailed a horseshoe above the door, or left scissors or knives beside the cradle. Behind these gestures lay a simple and ancient idea: the metal that humans had learned to forge with fire was stronger than the invisible presences they feared.
The Roman nail
In Rome the nail had a precise religious value. Livy, in the seventh book of his history, mentions an ancient law by which the chief magistrate was to drive a nail, on the Ides of September, into the wall of the temple of Capitoline Jupiter; according to the historian the custom also served to count the years. Livy also relates that in 363 BC, during a plague, a dictator was appointed for the sole purpose of driving the nail, because it was remembered that the rite had once stopped an epidemic.
The act of fixing, of nailing down, expressed the idea of blocking an evil, stopping it at a precise point. Pliny the Elder, in the Natural History, also records several beliefs connected with nails and iron objects, presenting them as customs widespread in his time without vouching for their effectiveness. In these cases the metal mattered less than the gesture that went with it.
The horseshoe and the legend of Saint Dunstan
The horseshoe combined several elements thought to be favourable: it was made of iron, it had the shape of a crescent moon and it was fixed with nails, often seven of them, a number considered lucky. In England a legend was told about Saint Dunstan, Archbishop of Canterbury in the tenth century and a skilled smith: the devil supposedly asked him to shoe his hoof, and the saint did so with such violence that he forced him to promise never to enter a place where a horseshoe hung.
The legend is attested much later than the saint's lifetime and should be read as a folk tale. The correct way to hang the horseshoe also varies from place to place: in some areas the points turned upward hold the luck in, in others the points turned downward pour it over the house.
Cold iron and the fairy folk
In British and Irish folklore iron, often called cold iron, was thought unbearable to fairies and spirits. A needle was sewn into a newborn's clothes, and an iron object was placed under the threshold or in the bed of a woman who had just given birth, to prevent the baby from being swapped for a changeling, the fairy creature that, according to belief, took the place of stolen infants. A common interpretation sees in these customs the memory of a time when iron was a new and powerful technology.
In Italy the gesture of touching iron survives as a joking formula, while the horseshoe still appears above doors and fireplaces. The history of this metal reminds us that protection, in popular culture, often relied on the tools of daily work: the nail, the blade, the farrier's shoe. They were familiar objects to which tradition attributed an extra strength, though no one ever demonstrated its effect.