Actual thought. Like the fact that your brain forms images like films, even of things you’ve never experienced before. The voice your brain has in your head, whether it’s your own or not. The way you can almost hear songs when you think of them. The way you can recall tastes and smells even if you aren’t experiencing them currently. The brain is so powerful, and we don’t even realize it until we’re lying in bed, desperate for sleep, or trying to focus on a task at work, and it goes off the rails and demands attention and awe.