Sellars holds, then, that the logical space of the sensible qualities has been successively recategorized in different stages of human development.  He proposes that this history will take one more turn as science develops further: unable to reduce or eliminate the sensibles, science will postulate a distinctive set of entities, sensa, to be the final embodiment of the sensible qualities, physical1 but not physical2.  Sellars is a physicalist about color, not because he thinks colors can be reduced to more basic properties and relations of physical objects, but because physics will have to expand to accommodate the sensible qualities, color included, as primitive entities.  