Sellars takes it that this claim states a structural feature of the manifest image.  It is, note, incompatible with views that reject the idea that there is a nonconceptual component in perception—which Sellars would think are confused about the place of sensible qualities in the manifest image.  The real challenge is filling in the placeholders in the above claim: what kind of thing that is in what kind of way a cube of pink in physical space is present in one’s perception, and how can it be present in a way other than as believed in?  