In physics, it seems like everything is ultimately reduced to a property. I used to believe that everything reduces down to matter and energy. But it seems as though matter and energy are made up of properties. For example, pure energy such as a photon, seems to be its parts/properties. Its spin, parity, stability etc. seem to be what it actually is. So then what is something which isn't a property? Do we just live in a world of properties and nothing else?