G i think your right, that sounds like the book.    if you mean a light that you perceive within,  it is not a spiritual book, its about how we see the way we do,  due to how the brain is wired.   everything we see on the outside is constructed by our brain , is made to appear the way it does, due to the brains wireing ,or programing.  i made the connection,  if the outside vision is (real) but in a sense all so illusionary, as it depends on the brain to decode it, or construct it, then all inner sensations,or psychic stuff  are of a similar design.