 Yet Spinoza is no orthodox Cartesian. He recognizes a variety of shortcomings in Descartes' physical views and moreover rejects much of the metaphysical foundation upon which these views rest. In light of these disagreements, Spinoza holds that bodies are not substances, but rather modifications of a single substance, and he develops a distinctive and novel view of their individuation. He must also find an alternative basis for the basic principles that underlie and explain the motion and interaction of bodies. The resulting physical view arguably contains anticipations of the fundamental character of modern physics, and certainly anticipates modern theory of homeostatic systems. Yet in spite of its express mechanistic and deterministic character, Spinoza's physical theory appears to exploit an irreducible element of finalism, and to accord an important explanatory role to individual bodily essences.