I haven't read the book, but if you can think of a time you said "My stomach is growling" - You're communicating that you are hungry, but doing so by creating an external entity with a mind of its own - your stomach, it's growling, not that you as a full organism are hungry, yet most people will completely understand the intent of your communication. I sometimes wonder if these sorts of ways of thinking are part of why such an idea as the bicameral mind was proposed, or if it's actually part of the way we think because of the legacy of such a bicameral mind.