Seconding this recommendation. The way the story was told became very surreal. It's an experience unlike any other that I've had while reading fiction.

FWIW, Dick claimed it was a record of communication with some cosmic intelligence named VALIS: Vast Active Living Intelligence System

Here's a thing TIL from the wikipedia entry:

> At one point, Dick claimed to be in a state of enthousiasmos with VALIS, where he was informed his infant son was in danger of perishing from an unnamed malady. Routine checkups on the child had shown no trouble or illness; however, Dick insisted that thorough tests be run to ensure his son's health. The doctor eventually complied, despite the fact that there were no apparent symptoms. During the examination doctors discovered an inguinal hernia, which would have killed the child if an operation was not quickly performed. His son survived thanks to the operation, which Dick attributed to the "intervention" of VALIS.