It is therefore not a formal question, but a question of empirical fact solely, whether, when you and I are said to know the 'same' Memorial Hall, our minds do terminate at or in a numerically identical percept. Obviously, as a plain matter of fact, they do _not_. Apart from color-blindness and such possibilities, we see the Hall in different perspectives. You may be on one side of it and I on another. The percept of each of us, as he sees the surface of the Hall, is moreover only his provisional terminus. The next thing beyond my percept is not your mind, but more percepts of my own into which my first percept develops, the interior of the Hall, for instance, or the inner structure of its bricks and mortar. If our minds were in a literal sense _con_terminous, neither could get beyond the percept which they had in common, it would be an ultimate barrier between them--unless indeed they flowed over it and became 'co-conscious' over a still larger part of their content, which (thought-transference apart) is not supposed to be the case. In point of fact the ultimate common barrier can always be pushed, by both minds, farther than any actual percept of either, until at last it resolves itself into the mere notion of imperceptibles like atoms or ether, so that, where we do terminate in percepts, our knowledge is only speciously completed, being, in theoretic strictness, only a virtual knowledge of those remoter objects which conception carries out. Is natural realism, permissible in logic, refuted then by empirical fact? Do our minds have no object in common after all?