 Our own percepts, images, and  sensations[6]  occupy a privileged place in this system of entities—they are “what is most indubitable in our knowledge of the world” (Russell 1927b: 139). This knowledge is of a “more intimate qualitative” (Russell 1927a: 389) kind; it reveals the intrinsic character of these entities. But our knowledge of the “physical world [the world constructed out of entities outside my experience] is purely abstract: “we know certain logical characteristics of its structure, but nothing of its intrinsic character” (Russell 1927b: 306–307).