I was prompted to read this after it popped up in a season 4 episode of LOST.
Horselover Fat is both the narrator and a third-person character. He is our everyman through whom we are led in a contemplation of the nature of reality, god and sanity. Was Fat really the recipient of a beam of pink light that contained information from god? Or is he just a psycho who speaks both as himself and as his alter, and more real ego, Philip K. Dick? Is god reincarnated in a two year old child? Was earth once populated by a race of three-eyed being? Will it be in the future? Is VALIS god or just a machine made by future humans? So much going on in terms of themes, ideas, and nothing much going on in terms of the sort of action one expects in a sci-fi book. Steroids for the imagination.