BOOK REVIEW / Are you feeling sleepy? It's only a magnetic crisis: 'From Mesmer to Freud: Magnetic Sleep and the Roots of Psychological Healing' - Adam Crabtree: Yale, 30 pounds

OF ALL the mysteries of the human mind, hypnotism is probably the most striking, yet least understood. Anyone who has seen a good stage hypnotist will know that suitable subjects can be manipulated in the most surprising ways. But academic psychology offers no satisfactory explanation for hypnosis. Nor is there very much serious investigation of its workings, outside the world of smoking cures and fringe psychotherapy.

Hypnotism is not a new subject. As Adam Crabtree makes clear, the phenomenon has been been recognised for more than 200 years. But from the beginning it was associated with outsiders and occult theories, and it has always been viewed with distrust by the scientific establishment. Crabtree describes how Franz Mesmer, an 18th-century physician, constructed an exotic theory of 'animal magnetism' to explain the trancelike reactions of patients he treated by laying on hands. Some of his followers were convinced that these 'magnetised' subjects gained powers of clairvoyance and telepathy; sceptics argued that it could all be explained by the suggestibility of the fashionable Parisians who flocked for treatment. There were also suspicions of sexual impropriety, for many accounts of 'magnetic crises' in female patients fell little short of the explicitly orgasmic.

So heated was the late 18th-century debate about mesmerism that in 1784 Louis XVI appointed a Royal Commission to investigate the craze. Among its members were Benjamin Franklin, then American ambassador to Paris, Antoine Lavoisier, the great chemist, and Dr Guillotin, whose eponymous invention would within a decade be the instrument of Lavoisier's death. The Commission's report attributed the behaviour of 'magnetised' subjects to imagination and imitation, but the tradition of animal magnetism continued to flourish, and Crabtree describes a century of further scientific commissions whose reports ranged from dismissive to generously agnostic.

As Crabtree tells the story, mesmerism provides the foundation for an 'alternate-consciousness paradigm'. Hypnosis and associated techniques allow the therapist to explore otherwise hidden centres of consciousness. Crabtree argues that this tradition has been largely eclipsed in the 20th century by the influence of Freudian psychoanalysis. While Freud himself used hypnosis at the start of his career, he later abandoned the technique, on the grounds that the unconscious is merely a misplaced aspect of a unified self, rather than a second consciousness in need of an independent channel of communication. However, Crabtree anticipates a resurgence of interest in the 'alternate-consciousness paradigm', because of the increasingly frequent diagnosis of multiple personality disorder in North America.

Crabtree's historical detail is always informative and entertaining, but his lack of critical distance at times borders on the credulous. Much of the latter part of the book is concerned with spiritualism, table turning and mysterious rappings. Crabtree does not explicitly endorse supernatural explanations of these phenomena, but he does not debunk them either, and one wonders why they are included, given their peripheral connection with psychotherapy. The book does much to remedy the current neglect of hypnosis and its therapeutic possibilities, but little to free it from its association with cranks and showmen.