We have observed the practice in the fourth century of building churches over the martyrs’ tombs. The natural reverence for their remains soon passed into a superstitious veneration and belief in their miraculous efficacy. Even such acute minds as those of Origen, Chrysostom, and Ambrose seem infected with this superstition.[233] It 138 soon became considered essential to the consecration of a church that it should be hallowed by some holy relics. These were placed not only on the altar, but in the sides of portals, to be kissed by the devout on entering.[234] The furnishing of these relics became a gainful trade. St. Augustine complains of certain vagabond monks who went about selling relics of the martyrs, if indeed martyrs they were.[235] In consequence of this practice a Theodosian law of the year A. D. 386 forbids the removal of any body that was buried, or the tearing asunder or sale of the remains of a martyr.[236] In consequence of the number of spurious relics, the fourth Council of Carthage, in A. D. 401, prohibited the use of any whose genuineness could not be authenticated.[237] Martin of Tours narrates how he discovered, by summoning the ghost of a so-called martyr, that the revered relics were only those of a common thief.[238] The Empress Constantina wrote to Gregory the Great, at the end of the sixth century, for the head 139 of St. Paul, in order to consecrate a new church. He replied that he could not divide the bodies of the saints, and declared that the danger of invading their tombs was sometimes even fatal.[239] But this pious reverence gave place to a more mercenary spirit, and the trade in relics became a traffic of infamy and disgrace. Not only were the bodies of the so-called martyrs torn asunder and their limbs sold to diverse and distant places, but with sacrilegious fraud the relics of favourite saints were multiplied till as many different cities claimed to have their only true and genuine heads, arms, or bodies, as contended for the honour of being the birth-place of Homer.[240]