Werner Herzog muses on mysteries of the brain in Theater of Thought

That mind is partly revealed through Herzog's running narration, such as when he muses about collective behavior and whether fish have souls—a digression sparked by his interview with Siri co-inventor Tom Gruber. "In the background, I saw his TV screen still on, we didn't switch it off, and I saw some very, very strange school of fish," said Herzog. "I asked him about the school of fish, which he had filmed himself. And all of a sudden, I'm only interested in the fish and common behavior. Why do they behave in big schools, in unison? Why do they do that? Do they dream? And if they think, what are they thinking about? I immerse the audience into a very strange form of underwater landscape and behavior of fish."

We glimpse the inner workings of Herzog's mind in the kinds of questions he asks his subjects, such as when he queries IBM's Dario Gil, who works on quantum computing, about his passion for fishing, eliciting an enthusiastic smile in response. He agrees to interview University of Washington neuroscientist Christof Koch after Koch's early-morning row on the Puget Sound and includes music from New York University neuroscientist Joseph LeDoux's band, the Amygdaloids, in the film's soundtrack. He asks married scientists Cori Bargmann and Richard Axel about music, their dinner conversations, and the linguistic capabilities of parrots. In so doing, he brings out their innate humanity, not just their scientific expertise.

"That's what I do. If you don't have it in you, you shouldn't be a filmmaker," said Herzog. "But you see, also, the joy of getting into all of this and the joy of meeting these scientists. We are talking about speaking parrots. What if two parrots learned a language that is already extinct and they would speak to each other? What would we make of it? So I'm asking, spontaneously, because I saw it, I sensed it, there was something I should depart completely from scientific quests. And yet there's a deep scientific background to it."