In Yogacara Mahayana buddhism there are three aspects of the Mind. See for example Buddhist thought by Paul Williams. The constantly changing flow of experiences is called the dependant aspect, the substratum of consciousness, the ultimate reality. What you experience when reading Brad's book could perhaps, according to Yogacara, be the funny shapes called letters triggering a reaction in your consciousness (the visual consciousness, the mental consciousness, the tainted mind and the constantly flowing substatum consciousness)? The substratum for this experience would then already be there, ever flowing, ever present, but also ever unseen and ever hidden as long as there is the constructed aspect (delusion, polarised subjects and objects) and the tainted mind that mistakes the substatum consciousness for a self. When one is rid of all delusions, there is the third aspect, the perfect aspect, which is the absense of the constructed aspect from the dependant aspect. Without the object-subject duality there is only the experience of the pure dependant aspect where everything is as it is, nothing unseen, nothing hidden.
A good author should use skilful means to put the right funny shapes on the paper according to the current state of mind and enlightenment of the reader.
I don't mean to tell you that this is the truth, just poitning at one philosophical way of looking at things.
Similar reasoning could probably be used in regard to Buddha nature, which I presume would be more Zen. :wink: