The Mouth of Truth (Bocca della Verità in Italian) is an ancient Roman marble disc with a relief carving of a man’s face. According to legend the face’s mouth closes if a liar sticks his hand in it.
The massive marble mask weighs about 1300 kg and probably depicts the face of the sea god Oceanus. The eyes, nostrils and mouth are open.
Historians aren’t quite certain what the original purpose of the disc was. It was possibly used as a drain cover in the nearby Temple of Hercules Invictus, which had an oculus – a round open space in the middle of the roof, similar to that of the Pantheon, hence it could rain inside. It is also thought that cattle merchants used it to drain the blood of cattle sacrificed to the god Hercules.
In the thirteenth century the disc was probably removed from the temple and placed against the wall of the Santa Maria in Cosmedin. In the seventeenth century it eventually moved to its current location inside the portico of the church.
The Legend of the Mouth of Truth
The marble disc is now famous for the medieval legend that is associated with it. People believed that the mouth of the marble face would close if anyone put his hand in it and told a lie. Therefore it was used as some sort of lie detector.
Those who were accused of committing perjury or adultery were brought here. They had to swear under oath and then put their hand into the mouth. According to the legend it was even used during the Middle Ages as a trial by ordeal. An executioner would hide behind the disc with a sharp sword ready to strike.
The legend became a popular part of culture and even today parents threaten fibbing children with a visit to the Mouth of Truth. In the nineteenth century the Italian writer Gioacchino Belli wrote a poem about the legend and the Mouth of Truth even entered American culture when it featured in the 1953 movie ‘Roman Holiday’.