Those who cannot accept the doctrine of mentalism have sometimes thought up very clever attempts to refute it. My friend, Professor Ernest Wood, once said to me that by leaving any object in a dark room and by turning a camera in its direction, fitted with a light and operated by a timing switch, so as to switch on the light in the absence of any human being in the room, a photograph of the object would thus be taken; and its existence apart from the thought of any human being would thus be proven. He said that an even simpler refutation of mentalism would be to walk over some rubbish in the dark which you did not know was there and to stumble over it. You could not possibly have thought of its existence, not knowing it was there, and yet it did exist! The answer to these clever criticisms is simple. Professor Wood, in the first case, had forgotten the person who had put the camera and the light in the dark room. That person had turned the camera towards the object and must surely have been thinking of the object. This, however, is only an answer to satisfy the requirements of logic; the real answer which philosophy gives is that the world-thought is given us by the Cosmic Mind--we do not create it. The presence or absence of any particular object within it does not therefore depend upon the individual thinking it, but his awareness of it will depend on this. The object in the dark room, the heap of rubbish in a dark street, exist for any individual's experience only so far as they come into his consciousness. Whether or not they exist for him at other times or for other men or for the Cosmic Mind does not and cannot alter this single fact--that his senses could never tell him about them unless his mind tells him about them, first and last.
-- Notebooks Category 21: Mentalism > Chapter 3: The Individual and World Mind > # 75