Yet in this cloud bank it is easy to see a whole world rising. A solid mountain range, a lake, a city, all rise in your imagination, and from the clouds the messengers of your perception return to you, assuring you that it is there. Figures stand out and move about, actions seem real, and forms appear and shift from loveliness to the grotesque. And back and forth they go, as long as you would play the game of children's make-believe. Yet however long you play it, and regardless of how much imagination you bring to it, you do not confuse it with the world below, nor seek to make it real.
(ACIM, T-18.IX.7.)

The blind become accustomed to their world by their adjustments to it. They think they know their way about in it. They learned it, not through joyous lessons, but through the stern necessity of limits they believed they could not overcome. And still believing this, they hold those lessons dear, and cling to them because they cannot see. They do not understand the lessons keep them blind. This they do not believe. And so they keep the world they learned to "see" in their imagination, believing that their choice is that or nothing. They hate the world they learned through pain. And everything they think is in it serves to remind them that they are incomplete and bitterly deprived. (ACIM, T-21.I.4.)