From the author of The Evolution of Consciousness (1991) and other popular works on the human mind, a revealing account of his own and others' prior misunderstandings about the right and left brains, a concise summary of current knowledge, and some provocative speculations about the development and functioning of the two hemispheres. The human brain is not unique in its asymmetry, psychologist Ornstein points out, for the divided cortex appeared with the first mammals. Further, fossil evidence from the pre-Jurassic period reveals creatures with right and left preferences, and even molecules have a directional orientation. But different we are, and he shows us how this has puzzled philosophers and scientists for centuries. Beginning in the 1970s, popular interest in the differences between the human brain's right and left hemispheres led to conflicting ideas, widespread misconceptions, misapplications by educators, and oversimplifications by social reformers. In a nutshell, the current view is that the right hemisphere gives us an overall view of the world, or the context, while the left provides the details, or the text. The loss of context seen in patients with right-brain damage leads Ornstein to reflect on the role of brain disequilibrium in such mental disorders as autism and schizophrenia. Noting that the human brain develops in response to its environment, he speculates that the differences in how the hemispheres operate may be traced to timing differences, i.e., the right hemisphere, maturing earlier, learns to handle low-frequency sounds, fuzzy images, and large movements, while the later-developing left hemisphere comes online when the baby is hearing spoken language and learning more precise movements. Ornstein, who illustrates his account with lots of quotes and stories, both sad and funny, is careful to distinguish between the research of others and his own freewheeling theorizing. Accessible and provocative, but surely not the last word.