place by which they flow in, others on the same side. There are also some which, having gone round altogether in a circle, folding themselves once or several times round the earth, like serpents, when they have descended as low as possible, discharge themselves again; and it is possible for them to descend on either side as far as the middle, but not beyond; for in each direction there is an acclivity to the streams both ways." "Now, there are many other large and various streams; but among this great number there are four certain streams, of which the largest, and that which flows most outwardly round the earth, is called Ocean; but directly opposite this, and flowing in a contrary direction, is Acheron, which flows through other desert places, and, moreover, passing under the earth, reaches the Acherusian lake, where the souls of most who die arrive; and, having remained there for certain destined periods, some longer and some shorter, are again sent forth into the generations of animals. 142. A third river issues midway between these, and, near its source, falls into a vast region, burning with abundance of fire, and forms a lake larger than our sea, boiling with water and mud. From hence it proceeds in a circle, turbulent and muddy, and, folding itself round it, reaches both other places and the extremity of the Acherusian lake, but does not mingle with its water; but, folding itself oftentimes beneath the earth, it discharges itself into the lower parts of Tartarus. And this is the river which they call Pyriphlegethon, whose burning streams emit dissevered fragments in whatever part of the earth they happen to be. Opposite to this, again, the fourth river first falls into a place dreadful and savage, as it is said, having its whole color like cyanus:[44] this they call Stygian, and the lake which the river forms by its discharge, Styx. This river, having fallen in here, and received awful power in the water, sinking beneath the earth, proceeds, folding itself round, in an opposite course to Pyriphlegethon, and meets it in the Acherusian lake from, a contrary direction. Neither does the water of this river mingle with any other; but it, too, having gone round in a circle, discharges itself into Tartarus, opposite to Pyriphlegethon. Its name, as the poets say, is Cocytus."