The idea of self-realization implies capacities or possibilities. To translate capacity into actuality, as the conception of the fixed self seems to do, is to vitiate the whole idea of possibility. There must, then, be some conception of unrealized powers which will meet this difficulty. The way to a valid conception is through the realization that capacities are always specific. "The capacities of a child, for example, are not simply of _a_ child, not of a man, but of _this_ child, not of any other."[105] Whatever else capacity may be, whether infinite or not, it must be an element in an actual situation. As specific things, moreover, capacities reside in activities, which are now going on. The capacity of a child to become a musician consists in this fact: "Even _now_ he has a certain quickness, vividness, and plasticity of vision, a certain deftness of hand, and a certain motor coordination by which his hand is stimulated to work in harmony with his eye."[106] How do these specific, actual activities come to be called capacities? There is a peculiar psychological reason for this which James has pointed out, in his statement that essence "is that _which is so important for my interests_ that, comparatively, other properties may be omitted."[107] When we pay attention to any activity, there is a natural tendency to select only that portion of it that is of immediate interest, and to exclude the rest as irrelevant. "In the act of vision, for example," Dewey tells us, "the thing that seems nearest us, that which claims continuously our attention, is the eye itself. We thus come to abstract the eye from all special acts of seeing; we make the eye the _essential_ thing in sight, and conceive of the circumstances of vision as indeed _circumstances_; as more or less accidental concomitants of the permanent eye."[108] There is no eye in general; the eye is always given along with other circumstances which in their totality make up a concrete seeing situation. Nevertheless, we abstract the eye from other circumstances and set it up as the essence of seeing. But we cannot retain the eye in absolute abstraction, because the concrete circumstances of vision force themselves upon the attention. So we lump these together on the other side as a new object, and take as their essence the vibrations of ether. "_The eye now becomes the capacity of seeing; the vibrations of ether, conditions required for the exercise of the capacity._"[109] We keep the two abstractions, but try to restore the unity of the situation through taking one as capacity and the other as the condition of the exercise of capacity.