In the world there are concrete particulars that exhibit the kind of substantial unity that allows them to be called substances or “natural individuals”, as opposed to artifacts or mere conglomerates. Persons, animals, and possibly the most fundamental physical simples are all natural individuals. What gives these entities the ontological status of a substantial unity? Arguments from the philosophy of mind and arguments from general metaphysics show that physical properties alone cannot account for substantial unity. The ultimate intrinsic properties of (...) natural individuals resemble phenomenal mental properties rather than any other kind of known properties. Pan(proto-)psychism is thus supported by systematically related arguments from different areas of philosophical inquiry. A certain amount of skepticism regarding the full nature of absolutely intrinsic properties is nevertheless well-advised. (shrink)