The Dream Master (1966), originally published as a novella titled He Who Shapes, is a science-fiction novel by Roger Zelazny. The novella won a Nebula Award in 1965.
The Dream Master is set in a future where the forces of overpopulation and technology have created a world where humanity suffocates psychologically beneath its own mass while abiding in relative physical comfort. This is a world ripe for psychotherapeutic innovations, such as the "neuroparticipant therapy" in which the protagonist, Charles Render, specializes. In neuroparticipation, the patient is hooked into a gigantic simulation controlled directly by the analyst's mind; the analyst then works with the patient to construct dreams--nightmares, wish-fulfillment, etc.--that afford insight into the underlying neuroses of the patient, and in some cases the possibility of direct intervention. (For example, a man submerging himself in a fantasy world sees it utterly destroyed at Render's hands, and is thus "cur
Source: http://en.wikipedia.org/wiki/Dream Master