The Geocosmos and the Interior of the Earth

The first of the three books containing Kircher’s cosmological vision of the world is Mundus subterraneus (The underground world) about the Earth, still considered as the center of the universe. The book begins with a long preface about his journey to Sicily and Calabria, with the sights of the Etna and Stromboli volcanoes, the earthquakes of Calabria, and his descent into the crater of the Vesuvius volcano. The first volume deals with the position of the Earth as the center of the universe, its composition, the water elements: oceans, seas, rivers, and fountains, the interior of the Earth with its subterranean fires and vents, and the terrestrial elements. It follows the structure of the Earth, especially its interior with its three systems of conducts of water, hydrophylacia, fire, pyrophylacia and air, aerophylacia. The water of all oceans, lakes, and rivers is said to communicate among them through the hydrophylacia. A “Central Fire” is located at the center of the Earth which distributes its heat through the whole Earth by means of the pyrophylacia. He deals with the nature, properties, and underground origin of lakes, rivers, and fountains and minerals or substances found on the Earth’s surface, their nature, properties, and uses, especially fossils, subterranean animals, dragons, men and demons, the presence of poisons and metals, chemistry and chemical works and the work of alchemists and their ability to transform metals, the panspermia, and the origin of plants and animals.