"Dreams are messages from the deep"
What a great classy way to open up the film. This is a direct quote from the books. It really sets the tone.
Reddit: In the later books they talk about genetic memory. Paul's prescience doesn't only go into the future, it extends into the past. He remembers every lifetime of every ancestor of Paul's that ever lived with such clarity that their personalities could manifest within him, if not suppressed. Herbert's philosophy was that some element of this existed in all of us. On an unconscious level we are aware of the forces that shaped our evolution, and the information learned from these formative experiences are felt as instincts and emotions. The "deep" is the unconscious well of humanitys' knowledge.