The investigations into the ever-changing history of our planet are among the most anticipatory intuitions to be found in the Codex Leicester. Leonardo takes the human body as the model for elucidating the physiology and dynamics of the Earth, which he views as a living organism subject to cyclical transformations. He thus distances himself from the Biblical narrative of the Creation of a perfect, eternally immutable world. He identifies water as the agent of continuous change, for it washes away mountainsides, carrying vast quantities of sediments to the sea. These material shifts would endanger the planet’s equilibrium if the hemisphere made lighter by erosion did not simultaneously witness the emergence of mountains. As on a scale, these offset the decrease in weight by their greater distance from the center of the world. Leonardo does not rule out the possibility that these offsetting processes could be interrupted, causing the Earth’s total submersion. At that point, he notes, without the slightest apparent emotion, “there would be no more land animals.”
we may say that the earth has had a spirit of growth, and that his flesh is the soil; its bones are the successive strata of the rocks which form the mountains; its cartilage is the tufa stone; its blood the veins of its water. The lake of the blood that lies around the heart is the ocean. Its breathing is […] the ebb and flow of the sea.