 Material atoms or corpuscles are indivisible in the sense that there is nothing within the world that is capable of reducing them into further parts. Corpuscles represent the lowest level of explanation that is possible within a mechanical account of bodies. Similar to the atomic level, the microphysical level lies beyond the boundaries of human perception. Wolff believes that although corpuscles are extended, fill space, and are endowed with the “force of inertia”, a precise statement of their size, magnitude, and shape cannot be empirically determined. It is unclear, for example, whether all corpuscles retain homogeneity with respect to their magnitude and shape. Yet because corpuscles are a species of composite beings, Wolff is confident that the essence of a corpuscle consists in the manner in which its parts are joined together. A corpuscle is an aggregate of atomic elements. Its component parts are simply the unextended points of force that occupy the atomic level.