 Bruno’s alternative theory of the elements drew on Pythagoreanism, ancient atomism, medieval discussions, pro and contra, of indivisible minims and Nicholas of Cusa’s elemental doctrines (BOL III, 510–536). Corporeal things comprised two material principles, earth and water, and two immaterial ones, spirit and soul. By “earth” Bruno meant the discrete, identical, irreducible spheres of which physical things were made. He often called them “atoms” to emphasize their indivisibility. The circumferences and centres of these spherical atoms coincided. Hence, as some medieval authors had proposed, atoms were dimensionless bodies, unlike the atoms imagined by Democritus and other ancient atomists. They were, as Bruno said, the principles of spatial contraction, of solidity. Water, by contrast, was a continuum and the principle of corporeal extension. Two or more atoms, though dimensionless, bonded by water constituted a determinate body in space, just as two or more dimensionless points, in Bruno’s Pythagorean geometry, constituted a line. “The minimal body or atom was the substance of all things” (BOL I.3, 140). Observation confirmed this theory: dry, dusty, earth congealed with the addition of water.