Even though caves may have been human's first homes, those deep, dark, depths still seem sinister and mysterious. In the Lord of the Rings, Saruman says of the caves of Moria that "you fear to go into those mines. The dwarves delved too greedily and too deep. You know what they awoke in the darkness of Khazad-dum... shadow and flame."
"All hope abandon, ye who enter in," is the warning at the mouth of the caves of hell in Dante Alighieri's Divine Comedy.
Descending into the Mammoth Cave, the longest known cave in the world, life on the surface fades away, and the intrepid spelunker is left alone in the dim halo of his headlamp.
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