The psychotic does not merely think he sees four blue bivalves with floppy wings wandering up the wall; he does see them. An hallucination is not, strictly speaking, manufactured in the brain; it is received by the brain, like any 'real' sense datum, and the patient act in response to this to-him-very-real perception of reality in as logical a way as we do to our sense data. In any way to suppose he only 'thinks he sees it' is to misunderstand totally the experience of psychosis.
Philip K. DickHow can days and happenings and moments so good become so quickly ugly, and for no reason, for no real reason? Just - change. With nothing causing it.
Philip K. DickDrug misuse is not a disease, it is a decision, like the decision to step out in front of a moving car. You would call that not a disease but an error in judgment. When a bunch of people begin to do it, it is a social error, a life-style. In this particular life-style the motto is "Be happy now because tomorrow you are dying," but the dying begins almost at once, and the happiness is a memory.
Philip K. Dick