In his boyhood, around the age of thirteen, Dick had a recurring dream for several weeks. He dreamed he was in a bookstore, trying to find an issue of Astounding Magazine. This issue of the magazine would contain the story titled "The Empire Never Ended", which would reveal the secrets of the universe to him. As the dream recurred, the pile of magazines he searched grew smaller and smaller, but he never reached the bottom. Eventually, he became anxious that discovering the magazine would drive him mad (as in Lovecraft's Necronomicon or Chambers' The King in Yellow, promising insanity to the reader). Shortly thereafter, the dreams ceased, but the phrase "The Empire Never Ended" would appear later in his work. Dick was a voracious reader of religion, philosophy, metaphysics and Gnosticism, ideas of which appear in many of his stories and visions.

Throughout February and March of 1974, he received a series of visions, which he referred to as "two-three-seventy four" (2-3-74), shorthand for February-March 1974. He described the initial visions as laser beams and geometric patterns, and, occasionally, brief pictures of Jesus and of ancient Rome. As the visions increased in length and frequency, Dick claimed he began to live a double life, one as himself, "Philip K. Dick", and one as "Thomas", a Christian persecuted by Romans in the 1st century A.D. Despite his history of drug use and elevated stroke risk, Dick began seeking other rationalist and religious explanations for these experiences. He referred to the "transcendentally rational mind" as "Zebra", "God" and, most often, "VALIS". Dick wrote about the experiences in the semi-autobiographical novels VALIS and Radio Free Albemuth.