DISASSOCIATING EARTH FROM MORALITY: RENE DESCARTES’ UNDERSTANDING OF EARTH’S INTERIOR

Western thought regarding earth’s interior has evolved slowly throughout history, and limited access to the subsurface presents a challenge to scientists still today. Reference to a central fire, and subterranean caverns, through which move rivers of fire, water and wind, are found in the writings of ancient Greek philosophers, such as Plato, Aristotle, and Seneca. A resurgence of these ideas occurred in the West during the 13^th century, through scholars such as Albertus Magnus, Roger Bacon, and Thomas Aquinas.

Until the work of Copernicus and Galileo, the earth was believed to be the center of the cosmos, the surrounding universe extending outward in concentric spheres. These layers were often considered morally hierarchical, the morality of each layer increasing with distance from the earth’s center. Both the Tartarus of Greek Mythology and the Christian Hell were thought to be located deep within the earth. The motion or topography of layers containing celestial bodies (e.g., planets, stars) were often thought to directly influence the earth’s surface, and parts of its interior (e.g., formation of metals). Surface features/events (e.g., volcanoes, springs, earthquakes) were also attributed to the motion or buildup of elements within subterranean passages.

René Descartes (1596-1650) sought to describe the formation of the earth through natural processes. Born a Catholic, Descartes published his ideas about earth’s formation under the guise of a thought experiment, to protect himself from a fate like Galileo’s. The interior of Descartes’ earth includes a central fire, surrounded by a layer of dense, earth-like matter, which is covered, in some areas, by subterranean water and air. A layer of less-dense earth – where people might live – encircle these, and outer layers of water and air – like our oceans and atmosphere – encompass all. Interaction between layers within the earth led to its surface features. For example, the outer earth layer collapsed downward, leaning against itself to form mountains. Descartes’ layers, although reflective of past ideas, did not carry moral value, and were meant to describe the natural differentiation of matter into a planet like the earth. His ideas bridge the gap between the Renaissance and the Scientific Revolution, and influenced the work of other scientists, such as Nicolas Steno.