Humanity dreams the same dream at once, and you have your mass world.
The whole construction is like an educational play in which you are the producers as well as the actors.
There is a play within a play within a play.
There is no end to the "within" of things.
The dreamer dreams, and the dreamers within the dreams dream.
But the dreams are not meaningless, and the actions within them are significant.
The whole self is the observer and also a participator in the roles.