It is asked why, if the world is like a dream or a hallucination, we all have the same dream or suffer the same hallucination. Why do we project it in common instead of independently, since we all do have quite different dreams when asleep at night or quite different reveries when awake by day? The answer is that there is another and vaster Mind behind our personal minds which imposes the same world-image upon them all, so that all see it and live in it. Moreover, they are of necessity themselves projected by this Mind so that this image is not less real for them than their own selves. The mind makes for itself this world of illusion, this stage of space and time and form. But it does not make it independently of all prompting. For the image that it constructs is imposed upon it--or projected into it--by the Mind behind it.
-- Notebooks Category 21: Mentalism > Chapter 3: The Individual and World Mind > # 64