Plutarch, Aemilius Paulus
Bernadotte Perrin, Ed.

14. But his men were annoyed especially by the lack of drinking water, since only a little of it issued forth and collected in pools at the very edge of the sea, and that was bad. Aemilius, therefore, seeing that the lofty and wooded mountain of Olympus lay near, and judging from the greenness of its trees that there were veins of water coursing under ground, dug a number of vents and wells for them along the foot of the mountain. [2] These were at once filled with streams of pure water, which, under the weight and impulse of the pressure that was upon them, discharged themselves into the vacuum afforded.

And yet some deny that stores of ready water lie hidden away beneath the places from which springs flow, and that they merely come to light or force a passage when they issue forth; they hold rather that the water is generated and comes into existence then and there through the liquefaction of matter, and that moist vapour is liquefied by density and cold, whenever, that is, it is compressed in the depths of earth and becomes fluid. [3] For, they argue, just as the breasts of women are not, like vessels, full of ready milk which flows out, but by converting the nourishment that is in them produce milk and strain it out; so those places in the ground which are chilly and full of springs do not have hidden water, nor reservoirs which send forth the currents and deep waters of all our rivers from a source that is ready at hand, but by forcibly compressing and condensing vapour and air, they convert them into water. [4] At all events, those places which are dug open gush and flow more freely in response to such manipulation, just as the breasts of women do in response to sucking, because they moisten and soften the vapours; whereas all places in the ground which are packed tight and unworked, are incapable of generating water, since they have not been subjected to the agitation which produces moisture. [5] But those who hold this doctrine give the sceptical occasion to object that, on this reasoning, there is no blood in living creatures, but it is generated in response to wounds by a transformation of some vapour or flesh, which causes its liquefaction and flow. Moreover, they are refuted by the experience of men who dig mines, either for sieges or for metals, and in the depths encounter rivers of water, which are not gradually collected, as must naturally be the case if they come into existence at the instant that the earth is agitated, but pour fourth in a great mass. And again, when a mountain or rock is smitten asunder, a fierce torrent of water often gushes forth, and then ceases entirely. So much on this head.