When you read a novel, a part of you is outside of the world of the novel (but ideally not very much so).

But when you you watch a movie or a play, you are completely immersed in the world of the story.

If screenwriters want their audience to become enmeshed in the screen story, they have to be willing to surrender themselves to the unthinking mode while they are creating the story. Revising is different, however. ("Write drunk, edit sober.")