ON THE ORIGIN AND CAUSES

For they say that this water flows from the sea. For that, as they say, having secretly entered into the hidden caverns of the earth, permeates through veins and veinlets, and is filtered by the very passage and course; having deposited its bitterness, it reserves for itself the simple and sincere taste of water, and again erupting openly from these same veins, it opens springs in many places. The waters of these, collected into rivers, return with a certain sweetness to the same sea from which they departed as salt water. The sea indeed soaks the earth with its liquid; for in some places it enters into subterranean caverns, and in some it penetrates under the lands through veins and veinlets; furthermore, it grants waters to certain maritime springs. Yet it is not poured into mountains higher than itself. For water naturally is not carried on high, but slides downward by its own weight. Because, therefore, the water not collected from rain that flows from mountains does not flow from the sea, not all water not collected from rains flows from it.

The other opinion is that such water is poured out from subterranean lakes. "For as," they say, "the exterior earth supports marshes, lakes, and seas, so the form and species of the interior are similar to it, and in its vast complexity, it contains, besides salt waters, a great force of fresh ones." Indeed, unless the earth had a supreme and perpetual abundance of waters of this kind, and always diffused it through veins as if from a full vessel, so many and such constant waters would not flow from springs. Although certain caverns are found in the earth made by the hand and work of man, or by the force of waters, winds, or fires, yet they do not pour out perennial waters from themselves; rather, they are sometimes filled by them. But as soon as they have been perforated, they release them from their prison in a short space of time. Then, if water flows from interior lakes, it is necessary that they be higher than the spring, or at least equally high. For water, whose nature and power it is to flow, where it arises in a higher place, erupts after having slid down from it; for which reason springs mostly gush forth at the roots of mountains. Where it is generated at an equal height, it exits by flowing; where it is in a lower place, it is not naturally carried to a higher one. This, not only an intelligent estimator, but any one of the miners can test. Now, if such lakes were higher than the springs, or equally high, those who dig mountains for the sake of metals would have found them, as I said above; but no such things have been found by them. Therefore, interior lakes do not always produce waters from themselves to pour them into the mouths of springs. From all of which it follows that not even one drop of water flows from such hidden lakes of the earth, much less all of it.

But the opinion of those who say that all water which is not rain is generated is this: it is generated in the earth from the air which it exhales, as soon as cold has driven out its heat. But because such matter is abundantly supplied to the earth, and cold likewise converts it into water, they seem to contend by reason that water is always being generated within the earth. They say that the same cannot happen in the celestial air, because it is perpetually...