What is the theme in Cosmic Trigger I: Final Secret of the Illuminati by Robert A. Wilson?

One of the themes of the book is that mind-altering drugs, though dangerous, can have a good effect in promoting research into the human mind. In Timothy Leary's theory of 8 levels of brain circuits, the main way to access the 4 higher circuits is by using drugs such as LSD. Under the influence of drugs, Wilson sees his first supernatural entity, the spirit of the drug plant mescaline, or Mescalito. Wilson's studies of Crowley's magic are just an extension of using drugs, and studying extraterrestrial phenomenon.