 This proposition is general and thus indirect with respect to the external object (in this case, the apple), but singular and thus direct with respect to the sense-datum being demonstratively referred to. For Russell, this is the canonical form all thought about external reality takes. Thought about concrete particulars is ultimately grounded in acquaintance, albeit acquaintance with sense data, and descriptive. (For a very intuitive presentation of this view, see chapter 5 of Russell 1912. For a more detailed presentation, see Russell 1910.)