Athanasius Kircher - Diagrams showing the interconnectedness of Fire and Water inside the Earth, “Mundus Subterraneus”, 1665.
Kircher stated that “the whole Earth is not solid but everywhere gaping, and hollowed with empty rooms and spaces, and hidden burrows.” Deep down, it holds many great oceans and fires, interconnected by a system of passageways that reached all the way to its core. In his view, volcanoes, however awful and awe-inspiring, “are nothing but the vent-holes, or breath-pipes of Nature,” and earthquakes are merely the “proper effects of subterrestrial cumbustions” that are sure to go on constantly. The “prodigious volcanoes and fire-vomiting mountains visible in the external surface of the earth do sufficiently demonstrate it to be full of invisible and underground fires,” he wrote. “For wherever there is a volcano, there also is a conservatory or storehouse of fire under it…. And these fires argue for deeper treasuries and storehouses of fire, in the very heart and inward bowels of the Earth.” According to Kircher, “the fire and water sweetly conspire together in mutual service.” The tides, caused by the nitrous effluvia of the moon, push “an immense bulk of water” through “hidden and occult passages at the bottom of the Ocean” and thrust it “forcibly into the intimate bowels of the Earth.” The resulting winds “excite and stir up” and otherwise feed the subterraneous fire like a huge bellows. The seas, which would stagnate and freeze without the fires, keep the fires from getting out of hand, preventing “unlimited eruptions,” which would “soon turn all to ruins.” The “secret make-up of the mountains” is that they are hollow and serve as reservoirs. Hot baths, hot springs, and fountains are produced where underground water passageways come near or interconnect with the fire channels.
More than once, Kircher compares the movement of the earth’s water to the circulation of the blood in the body as described by William Harvey. The water of the oceans follows its “secret motions” up and around the globe toward the North Pole. Somewhere off the coast of Norway (the actual site of a major whirlpool system called the Moskenstraumen), he declared, is a giant maelstrom through which the water enters the earth - as if passing through a great drain - and runs through it, cooling it down, providing it with nutriments in particulate form before being eliminated through a nether opening at the South Pole. Sometimes the analogies referred more to the continuing process of the digestive system than the cycling of blood, but no matter: “You see therefore the manner and way of the Circulation of Nature.”