ON THE ORIGIN AND CAUSES

that it is sufficient and is not consumed before it increases again in winter, are perennial. But those with smaller receptacles dry up because of the scarcity of water, their vessel being emptied before water flows down from the sky again.

Certainly, as far as the former opinion is concerned, that middle and torrid belt has few springs and not many rivers, whereas the habitable northern belt, and the southern one opposite it, have very many both of springs and rivers. But even if the matter is thus, it does not follow that water has no other origin. For whence would come the constant springs of those few rivers? It is not reported that all of them are led into those torrid regions from faraway places, but that some arise within them. For, as geographers have left written regarding this matter, the Niger flows from Mount Thala, and the Masitholus from that which they call the vehicle of the gods. These mountains of interior Libya, since it rains for only a few months of the year and they have almost continuous and perennial summer, would necessarily lack constant waters.

Indeed, if in the Hellespont and other places subject to the same circle of longitude, some springs and brooks often dry up in the heat of summer, and even in our own regions during great and lasting drought, they would all dry up in such a climate—which is almost perpetually summer—if the mountains generated no water within themselves but merely poured out rain in the way they had conceived it. But they do not all dry up; therefore, not all of their water is collected from rain. Nor will it be correctly said that such mountains drink up snow melted by heat, which they would not lack because of their height, and that for this reason the springs within them are constant. For even if so hot a climate were to generate snow—which it generates less than rain—the accession of waters to the Niger and Masitholus would happen only when those snows were melted, just as the flooding of the Nile refers to the theories of Anaxagoras regarding the source of the Nile's flooding—if indeed Anaxagoras of Clazomenae felt correctly about its increase, and those who followed his authority. Since, therefore, snows only increase rivers with water and are not the cause of their perpetuity, and the rivers of which I spoke are perennial, we understand them to arise from constant waters, which it is certain are found within the earth in the driest places by well-diggers. For if at any time they dig wells deep to two hundred or at most three hundred feet, rich veins of water leap forth from their bottom or sides.

Aristotle refutes the other opinion thus: "But," he says, "it is clear that he who would make and place before his eyes a receptacle for water flowing continuously every day could conceive its magnitude in his mind. For that water, which it collected over the course of a year, would exceed the mass of the earth in size, or not fall far short of it." Nor is there any doubt that many things of this kind occur everywhere in the lands. We can also say these things against the same opinion: if that vessel or receptacle of waters is below the springs, it cannot pour waters into the spring-mouths, as they, because of their own weight, are not carried on high. If it is above the springs, then it could emit waters from itself like a castle, but miners, who have thoroughly overturned certain mountains, would have already found it. However, none has been found. Therefore, either it does not exist, or, if any exists, it cannot be the cause of any spring. It follows, therefore, that not all spring and well water is collected from rain.