Here’s a great interview Mike Mills gave on Bullseye with Jesse Thorn, in which Mills discusses how working on his most recent film, C’mon C’mon, was almost an act of summoning something otherworldly.

“I don’t think I’m in any control of what I make or what I do. I feel like you summon things, but you summon…whole beings. The film, the script, the cosmos of [C’mon C’mon], it kinda came from me and my kid, but it’s like its own weird entity…I think Mr. Fellini would say this too.”
In the book, Fellini on Fellini, the renowned Italian filmmaker does, in fact, agree with Mills. He writes, “a film is a living reality: sometimes its orders must be obeyed, sometimes one must recall it to its own internal rhythm…I go to a story to discover what it has to tell me.”

“It’s learning how to ride that wave,” Mills continues. “Or understanding that it’s not totally under your control and that it is this kind of from-the-cosmos, spiritual entity blob that you’re helping fertilize and bring forth. And it’s part you, but equally not you.”
Perhaps ideas do come somewhere else. Or perhaps that come from deep within consciousness (as David Lynch claims). Either way, surrendering to an idea when it wants to take charge seems to yield the best result.