Mention of the Great Deep reminds us of yet another prolific source of the spectral element in Syrian thought. It was but natural that the sound of underground rivers and their explanation by the theory of a world founded on bottomless floods (the “waters underneath the earth”), should have given to the whole land an air of possession by ghostly powers. It may have been that same phenomenon which drew down the imagination of Syria to the subterranean regions, or it may also have been to some extent the hereditary greed of buried treasure, which every nation whose buildings have been often overturned is likely to acquire. Whatever be its explanation, the fact is certain that the underground element is one which counts for much in the spirit of Syria. Alike in Christian and in pre-Christian times there seems to have been a most unwholesome dread of fresh air blowing about holy things. Sacred caves and pits were among the most characteristic properties of ancient Semitic religion.[52] As for Christian tradition, it seems positively to dread the open air. The Nativity in Bethlehem and the Agony in Gethsemane have each their cave assigned to them, and many another site has a cave either discovered or actually constructed for its commemoration. Nature and history have combined to encourage the underground tendency. Palestine is remarkable for the number and size of its natural caverns, and it is not slow to add its imaginative touch to the length of them, connecting distant towns with supposed subterranean passages. These caves have been used as dwelling-places from very ancient times. The strange cities of Edom and of Bashan are well known to all as wonders. And not in these places only, but in many other parts of the land, men have dwelt beneath the ground. In times of invasion, for the solitude of hermit life, and in the terrors of persecution, caves have offered natural places of refuge and of hiding, which have in many cases been greatly enlarged by excavation. Besides those caverns whose interest lies in the memory of ancient inhabitants, there are some of an interest whose terror is not yet departed. These are the cave-dwellings of lunatics, who in former times often chose the dead for company and inhabited tombs. Now, in some places they are chained in black recesses of mountain caverns, where their life must be horrible indeed. There are also one or two caves in Syria which end in sudden perpendicular shafts of great depth, where adulteresses are said to meet their fate. Such modern instances may have reinforced the natural fascination of the occult which subterranean places offer. But there is something congenial to it in the spirit of Syria quite apart from these.