A better subtitle for this book might have been 'A Cultural History of Hypnosis', as this would alert prospective readers to the kind of work it is. I would certainly recommend checking the bibliography before buying, as it includes a lot of junk, interesting in a cultural sense perhaps but misleading to the untutored and potentially annoying to those of a sceptical frame of mind.
Waterfield is a generalist who does not necessarily handle scientific literature well. Esoteric sympathies are hinted at on the dust jacket, where he is described as having 'a lifelong interest in human potential' (I assume this is code). He has written a sympathetic biography of the author of 'The Prophet' as well as a lot on the ancient world, but this seems to be his only foray into the rigours of science.
I picked this book up in the hope of reading a dispassionate account but was put off by new age wooziness and some downright weird sections on, oh dear, multiple personality disorder and Russian psychics. Still waiting for a book on the hypnosis phenomenon by, say, Simon Singh or Ben Goldacre.