Everything points to the conclusion that this infernal theology developed in the East. The Egyptians described at length in the “Book of the Dead” the pains of those who despised the precepts of Osiris, and illustrated these sufferings with pictures. The only pagan writing in which we find a classification of sinners and of their torments, analogous to that contained in the revelation of the apocryphal gospel of Peter, is the Mazdean “Book of Arta Viraf,” which, although of late date, has antecedents which certainly go back very far. The Persian religion, which more than any other brings the Spirit of Evil and his hordes of demons into relief, was certainly not unconnected with the development of infernal eschatology, even in the West, as is indicated by the fact that these demons succeeded the Furies as executors of the divine sentences. It was under the influence of these exotic religions that the descriptions were propagated of refined tortures, terrifying to the adepts of the conventicles in which they were revealed. The mysteries which spread under the Roman Empire accentuated the contrast between the delights of heaven and the sufferings of hell. These esoteric sects gave birth to the literature which was to be perpetuated through the Middle Ages, and inspire numbers of visionaries, poets and artists. Certain authors of treatises on demonology in antiquity must have revelled in inventing unheard-of atrocities, as later the hagiographers took pleasure in describing the inconceivable torments inflicted on martyrs. Among all the forms of punishment that by fire predominates. The idea that the Erinyes burnt the damned with their torches is ancient, and the Pyriphlegethon is an igneous river surrounding Tartarus. Certain authors went beyond this. Lucian in his “True Histories” describes the island of the impious as an immense brazier whence rise sulphurous and pitchy flames. Thus was born into the world in the Greco-Roman period a doctrine which was to survive its fall and last to modern times. The ancients certainly connected this infernal fire with the treatment inflicted on those condemned to be burnt alive; but this exceptional punishment could not inspire an eschatological conception which included all the dead. The opinion has been advanced that the choice of fire was due to the belief that this element purifies.[436] Fire would have been at first the means of destroying, in the Beyond as in this world, the uncleanliness of souls, before it became the instrument of their eternal torture. But a scientific theory seems here to have influenced religious faith. The physicians admitted the existence of an incandescent mass in the interior of the earth, which produced volcanic eruptions and hot springs. As Tartarus was situated in the uttermost depths of the underworld, it was conceived as a vast brazier in which the sulphur and bitumen vomited by the volcanoes were boiling for the punishment of sinners.[437]