upon stone and hard rock and draws vigor from these as other fires do from dry wood. And never is rock or stone so hard but that this fire will melt it like wax and then burn it like fat oil. But when a tree is cast upon the fire, it will not burn but be scorched only. Now since this fire feeds on dead things only and rejects everything that other fires devour, it must surely be said that it is a dead fire; and it seems most likely that it is the fire of hell, for in hell all things are dead. Footnote 212: _Dialogorum Libri_ IV. Pope Gregory died in 604. The Icelandic version of Gregory’s _Dialogues_ is published in _Heilagra Manna Sögur_, I. Footnote 213: It is difficult to determine whether the author uses “places of torment” as a term for hell or for purgatory; it seems probable, however, that in this case hell is meant. I am also disposed to believe that certain bodies of water in Iceland must be of the same dead nature as the fire that we have described. For there are springs which boil furiously all the time both winter and summer. At times the boiling is so violent that the heated water is thrown high into the air. But whatever is laid near the spring at the time of spouting, whether it be cloth or wood or anything else that the water may touch when it falls down again, will turn to stone. This seems to lead to the conclusion that this water must be dead, seeing that it gives a dead character to whatever it sprinkles and moistens; for the nature of stone is dead. But if the fire should not be dead but have its origin in some peculiarity of the country, the most reasonable theory as to the formation of the land seems to be that there must be many veins, empty passages, and wide cavities in its foundations. At times it may happen that these passages and cavities will be so completely packed with air, either by the winds or by the power of the roaring breakers, that the pressure of the blast cannot be confined, and this may be the origin of those great earthquakes that occur in that country.[214] Now if this should seem a reasonable or plausible explanation, it may be that the great and powerful activity of the air within the foundations of the earth also causes those great fires to be lit and to appear, which burst forth in various parts of the land.[215] Footnote 214: For the history of this theory see above, pp. 17–18. Footnote 215: The number of volcanoes in Iceland is variously given, but the more reliable authorities give 107.