When you have passed the Styx, you soon meet another stream, appropriately called Lethe. The echoes here are absolutely stunning. A single voice sounds like a powerful choir; and could an organ be played, it would deprive the hearer of his senses. When you have crossed, you enter a high level hall, named the Great Walk, half a mile of which brings you to another river, called the Jordan. In crossing this, the rocks, in one place, descend so low, as to leave only eighteen inches for the boat to pass through. Passengers are obliged to double up, and lie on each other's shoulders till this gap is passed. This uncomfortable position is, however, of short duration, and you suddenly emerge to where the vault of the cave is more than a hundred feet high. In the fall of the year, this river often rises, almost instantaneously, over fifty feet above low-water mark; a phenomenon supposed to be caused by heavy rains from the upper earth. On this account, autumn is an unfavorable season for those who wish to explore the cave throughout. If parties happen to be caught on the other side of Jordan, when the sudden rise takes place, a boat conveys them, on the swollen waters, to the level of an upper cave, so low that they are obliged to enter on hands and knees, and crawl through. This place is called Purgatory. People on the other side, aware of their danger, have a boat in readiness to receive them. The guide usually sings while crossing the Jordan, and his voice is reverberated by a choir of sweet echoes. The only animals ever found in the cave are fish, with which this stream abounds. They are perfectly white, and without eyes; at least, they have been subjected to a careful scientific examination, and no organ similar to an eye can be discovered. It would indeed be a useless appendage to creatures that dwell for ever in Cimmerian darkness. But, as usual, the acuteness of one sense is increased by the absence of another. These fish are undisturbed by the most powerful glare of light, but they are alarmed at the slightest agitation of the water; and it is therefore exceedingly difficult to catch them.