Though fear lurked strongly within him, Dick insisted on staring madness in the face and asking if it, too, could lay claim to a kind of knowledge. Thus, in "Drugs, Hallucinations, and the Quest for Reality," a 1964 essay included herein, Dick argued that what is called schizophrenic or psychotic "hallucination" may be, in many cases, the result of extremely broad and sensitive perceptions that most "sane" persons learn to screen out of their consciousness. The Kantian a priori categories of space and time are examples of such screens; Kant claimed that these were necessary for the mental ordering of phenomenal reality, which would otherwise remain a hopeless perceptual chaos to human minds. In his essay, Dick theorized that, to the extent that our mental and sensory awareness happens to extend beyond these socially ratified screens, any one of us may become subject to "hallucinations" -- which are, in essence, unshared realities. While it is possible that "mystical" insights may ensue, there is a greater likelihood -- and a fearfully tragic one it is -- that we may find ourselves in a hell realm of utter mental isolation:

In the light of this, the idea of hallucinating takes on a very different character; hallucinations, whether induced by psychosis, hypnosis, drugs, toxins, etc., may be merely quantitatively different from what we see, not qualitatively so. In other words, too much is emanating from the neurological apparatus of the organism, over and beyond the structural, organizing necessity... . No-name entities or aspects begin to appear, and since the person does not know what they are -- that is, what they're called or what they mean -- he cannot communicate with other persons about them. This breakdown of verbal communication is the fatal index that somewhere along the line the person is experiencing reality in a way too altered to fit into his own prior worldview and too radical to allow empathic linkage with other persons.