assertions. But is not our actual life of assertions about actual fellow-beings much like a dream to which there should happen to correspond some real scene or event in the world? Such correspondence would not make the dream really “true,” nor yet false. It would be a coincidence, remarkable for an outside observer, but none the less would the dreamer be thinking in his dream not about external objects, but about the things in his dream. But is not our supposed Thomas so and only so in the thought of John as he would be if John chanced to dream of a Thomas that was, to an external spectator, like the real one? Is not then the phantom Thomas, John’s only direct object, actually a thing in John’s thought? Is then the independent Thomas an object for John in any sense?
Yet again. Let us suppose that two men are shut up, each in a closed room by himself, and for his whole life; and let us suppose that by a lantern contrivance each of them is able at times to produce on the wall of the other’s room a series of pictures. But neither of them can ever know what pictures he produces in the other’s room, and neither can know anything of the other’s room, as such, but only of the pictures. Let the two remain forever in this relation. One of them. A, sees on his wall pictures, which resemble more or less what he has seen in his own room at other times. Yet he perceives these to be only pictures, and he supposes them to represent what goes on in another room, which he conceives as like his own. He is interested, he examines the phenomena, he predicts their future changes, he passes
