A U.K. mental health consultant and clinical director with a background in literature, McGilchrist attempts to synthesize his two areas of expertise, arguing that the "divided and asymmetrical nature" of the human brain is reflected in the history of Western culture. Part I, The Divided Brain, lays the groundwork for his thesis, examining two lobes' significantly different features (structure, sensitivity to hormones, etc.) and separate functions (the left hemisphere is concerned with "what," the right with "how"). He suggests that music, "ultimately... the communication of emotion," is the "ancestor of language," arising largely in the right hemisphere while "the culture of the written word tends inevitably toward the predominantly left hemisphere." More controversially, McGilchrist argues that "there is no such thing as the brain" as such, only the brain as we perceive it; this leads him to conclude that different periods of Western civilization (from the Homeric epoch to the present), one or the other hemisphere has predominated, defining "consistent ways of being that persist" through time.
Neat. Also could be explained by the verbal/spatial split in intelligence: dying civilizations produce people with high verbal but low spatial, although most of them think they have high spatial intelligence as they memorize things invented by others.