Athanasius Kircher · 1665
Read the translation (PDF) · Editorial footnotes (PDF)
A vast attempt to explain the whole hidden world beneath our feet. Drawing on a daring descent into the smoking crater of Vesuvius and a lifetime of reading, it describes a planet riddled with fiery channels and underground rivers, ranging across volcanoes, springs, tides, metals, minerals, fossils, poisons, subterranean creatures, and the secrets of alchemy.
The work is in XII libros digestus — set out in twelve books — and it begins further back than its title suggests. The first book is Centrographicus, on the centre: a sequence of definitions, canons and corollaries on centres of gravity and of magnitude, establishing the geometry of a body’s centre before Kircher descends into the particular body that is the Earth. From that foundation the books move outward through the planet’s fires and waters to its metals, minerals, fossils, poisons and subterranean creatures, and finally to alchemy and the transmutation of substances.
The book is famous for its engravings, above all the cross-section of a globe threaded with fire and burning at its core — one of the most reproduced images in the history of the earth sciences, and the picture most people carry of what the seventeenth century thought the underground looked like.
Mundus Subterraneus is the foundational synthesis of early modern earth science, and it is valuable precisely because it does not sort cleanly into what later ages kept and what they discarded. The volcanic observation is first-hand and hard-won; the hydrology is a serious attempt to account for springs, tides and the circulation of water through the Earth; and both sit alongside Hermetic and biblical speculation without apology. Reading it is the most direct way to see how a learned seventeenth-century mind actually held those things together, rather than how later summaries have separated them.
The translated source is the 1665 printing. Its front matter records the standing of a work of this scale in Counter-Reformation Europe: approbations from the author’s order, an engraved portrait of and dedicatory epistle to Pope Alexander VII, and printing privileges granted by both the Holy Roman Emperor and Charles II of England.