In the porch of the interesting old church of Sta. Maria in Cosmedin near the Tiber is preserved a huge circular stone like a millstone. It is composed of white marble, upwards of five feet in diameter, and is finished after the model of the dramatic mask used in the ancient theatres. In the centre is a round hole perforating the mass right through, forming the mouth of the mask. It is called the Bocca della Verita, and has given its name to the irregular piazza in which the church is situated. It is so called from the use to which it has been put from time immemorial, as an ordeal for testing the guilt or innocence of an accused person. If the suspected individual on making an affirmation thrust his hand through the hole and was able to draw it back again, he was pronounced innocent; but if, on the contrary, the hand remained fixed in the marble jaws, the person was declared to have sworn falsely and was pronounced guilty. The marble mouth was supposed by the superstitious to contract or expand itself according to the moral character of the arraigned person. No reason has been given why this singular marble mask should have been placed in this church, nor is anything known of its previous history. Some have conjectured that it served as an impluvium or mouth of a drain in the centre of a court to let the water run off; and others regard it as having been an ornament for a fountain, like the colossal mask of marble out of the mouth of which a jet of water falls into a fountain in the Via de Mascherone, called after it, near the Farnese Palace, and the marble mask which belongs to a small fountain on the opposite side of the river near the Palazzo Salviati. But the question arises, Why should the Bocca della Verita, if such was its origin, have been used for the superstitious purpose connected with it? Our answer to this question must lead us back to the Temple of Ceres and Proserpine which originally stood on the site of the church of Sta. Maria in Cosmedin, and of the materials of which the Christian edifice was largely built.

In primitive times the worship of clefts in rocks, holes in the earth, or stones having a natural or artificial perforation, appears to have been almost universal. We find traces of it in almost every country, and amongst almost every people. These sacred chasms or holes were regarded as emblems of the celestial mother, and persons went into them and came out again, so as to be born anew, or squeezed themselves through the holes in order to obtain the remission of their sins. In ancient Palestine this form of idolatry was known as the worship of Baal-perazim, or Baal of the clefts or breaches. David obtained a signal victory over the Philistines at one of the shrines of this god, and burnt there the images peculiar to this mode of worship which the enemy had left behind in its flight. About two miles from Bombay there is a rock on the promontory of the Malabar Hill, which has a natural crevice, communicating with a cavity below, and opening upon the sea. This crevice is too narrow for corpulent persons to squeeze through, but it is constantly resorted to for purposes of moral purification. Through natural or artificial caverns in India pilgrims enter at the south side, and make their exit at the northern, as was anciently the custom in the Mithraic mysteries. Those who pass through such caves are considered to receive by this action a new birth of the soul. According to the same idea the rulers of Travancore, who are Nairs by caste, are made into Brahmins when they ascend the throne by passing through a hole in a large golden image of a cow or lotus flower, which then becomes the property of the Brahmin priests. It is possible that there may be an allusion to this primitive custom in the rule of the Jewish Temple, mentioned by Ezekiel,—"He that entereth in by the way of the north gate to worship shall go out by the way of the south gate; and he that entereth by the way of the south gate shall go forth by the way of the north gate: he shall not return by the way of the gate whereby he came in, but shall go forth over against it." This arrangement may have been made not as a mere matter of convenience, but as a survival of the old practice of "passing through" a sacred cave or crevice for the forgiveness of sins;—a survival purified and ennobled in the service of God.