My old acting teacher, Maggie Flanagan, used to say, "Go where you don't know, into what you don't understand."
I always interpreted that as being about accessing the unconscious. Art doesn't come from well articulated, fully understood ideas. It comes the thing that gets under your skin and you don't know why.
I always know what my next play will be because it's the idea/image/thought/character/phrase that I can't explain but can't shake off.