Schizophrenia is one of the most devastating and mysterious mental illnesses. People with schizophrenia have the unique sensation that their brain is being taken over by external entities and that their heads are filled with voices that are not their own. Although it is increasingly recognized as a biological illness of the brain, it also has profound psychological implications for how we perceive reality.

The Madness Within Us: Schizophrenia as a Neuronal Process is an illuminating discussion of these two aspects of the illness. Dr. Robert Freedman, who is both a neuroscientist...