It is, indeed, no wonder that legends and poetical fancies such as these should cluster round caves, for the gloom of their recesses, and the shrill drip of the water from the roof, or the roar of the subterranean water-falls echoing through the passages, and the white bosses of stalagmite looming like statues through the darkness, offer ample materials for the use of a vivid imagination. The fact that often their length was unknown, naturally led to the inference that they were passages into another world. And this is equally true of the story of Boabdil, of that of the Purgatory of St. Patrick, in the north of Ireland, and of the course of the river Styx, which sinks into the rocks and flows through a series of caverns that are the dark entrance-halls of Hades. The same idea is evident in the remarkable story, related by Ælian (Lib. xvi. 16). “Among the Indians of Areia there is an abyss sacred to Pluto, and beneath it vast galleries, and hidden passages and depths, that have never been fathomed. How these are formed the Indians tell not, nor shall I attempt to relate. The Indians drive thither (every year) more than 3,000 different animals--sheep, goats, oxen, and horses--and each acting either from dread of the dreadful abyss, or to avert an evil omen in proportion to his means, seeks his own and his family’s safety by causing the animals to tumble in; and these, neither bound with chains nor driven, of their own accord finish their journey as if led on by some charm; and after they have come to the mouth of the abyss they willingly leap down, and are never more seen by mortal eyes. The lowing, however, of the cattle, the bleating of the sheep and of the goats, and the whinnying of the horses are heard above ground, and if anyone listen at the mouth, he will hear sounds of this kind lasting for a long time. Nor do they ever cease, because beasts are driven thither every day. But whether the sound is made by those recently driven in, or by some of those driven in some time before, I do not express an opinion.” The Roman Catholic Church took advantage of this feeling of superstitious awe, as late as the Middle Ages. At the time of the Reformation it was believed that a cave at Bishofferode would prove the death of some person in the course of the year, unless a public yearly atonement were made. Accordingly a priest came, on a certain day, to the chapel on the hill opposite, whence he passed in solemn procession to the cave, “and let down into it a crucifix, which he pulled up again, and took this occasion to remind them of hell, and to avoid the punishment due to their sins.”