One of the goals seems to be to destigmatize hallucinations, which owe much of their stigma to cultural fear of the most devastating types (i.e. schizophrenia). That may be why Sacks intentionally leaves schizophrenia out of his otherwise exhaustive list of varieties of hallucinations. The point being to distance hallucinations --as a genre --from the stigma of mental illness, not to destigmatize mental illness itself. The stigma against mental illness remains in tact by its omission. In the attempt to correct the misdiagnosis of hallucinations as only symptoms of mental illness, the psychological causes of some of these hallucinations is almost completely ignored, except in such obvious comments as "a child may create an imaginary friend because he is lonely." The idea seems to be that if hallucination is the result of a physical diagnosis like epilepsy then it need not be stigmatized. This book is organized as a list, without any comparison or contrast, or any connection between the types of fugitive visions on the list. A child's imaginary friend, grand mal seizures, PTSD, and quasi dream states are lumped together, like making a list of apples, roses, and rubies because they are all red. Granted, this is a popular rather than a scientific work. 90% of the book is anecdotes (which in scientific parlance means unreliable). Some anecdotes would be fine, but there is almost no discussion of the neurological mechanisms of hallucinations. The author ignores the fact that there are extremely diverse causes and effects of the anecdotal stories. Discussing the significant differences between the specific causes of the different types of hallucinations would lead to the different areas of the brain they effect. The book leaves the impression that all hallucinations derive from the same mechanism in the brain. There are compromises when writing about science for a lay audience, but the basic terminology here is pretty sloppy. Throughout, all kinds of terms are used for "hallucination" (e.g. visions) which also contributes to the hodgepodge effect.

Seeing, hearing, smelling, or touching things that aren't there isn't normal, right? Maybe not, but it's hardly uncommon. In fact, according to neurologist Oliver Sacks, there are many reasons that people might be deceived by their own senses. Some hallucinations are temporary, the result of substance abuse, injury, or sensory deprivation. Others are symptomatic of underlying conditions or disorders such as epilepsy, Parkinson's, or even Charles Bonnet Syndrome (in which memories fill the gaps left by the parts of the brain responsible for vision). In this intriguing collection of case studies, Sacks examines real-life hallucinations, past and present, from Dostoyevsky's epileptic visions to the author's own experiments with drugs -- which resulted in a conversation with a spider about mathematician Betrand Russell. Nature and Science newsletter December 2012 http://www.nextreads.com/Display2.aspx?SID=5acc8fc1-4e91-4ebe-906d-f8fc5e82a8e0&N=581853

terrific piece of work - very readable, well footnoted with wonderful quotes and stories of things seen... a great mix of anecdotes and science - you won't be disappointed...