BULLA. - A lenticular capsule, empty inside, formed of two superimposed plates and provided with a loop so that it could be worn around the neck. Sometimes it also takes the form of a heart or a crescent. It was in general use among the Etruscans, who attributed prophylactic powers to it. From them the Romans adopted it, among whom it was worn by freeborn children and youths, both male and female, as those who were most exposed to the influences of the evil eye and of spells. It was made of metal, often precious, for the children of patrician senators and knights, and of leather for the others. It generally contained within itself objects endowed with special prophylactic powers. It was laid aside and offered to the lares in the seventeenth year, when boys assumed the toga virilis, and at about the same age by girls, when they married. The faces of the bulla were ordinarily smooth, but sometimes those made of metal were adorned with repoussé reliefs, mostly busts of children or divinities.
Among the Christians of the first centuries the use of bullae also continued, more out of custom than out of superstition. They sometimes adorned the front face of them with Christian representations, especially with the christological monogram. And it seems that they often placed inside them relics of holy martyrs, so as to make of them true reliquaries, or else small sheets of parchment with invocations and exorcisms against the powers of darkness.