In the first half of this book, Oliver Sacks has talked about cases in which there is a clear neurological excess or deficit—and cases in which, clearly, “something is the matter.” In Part Three, Sacks will discuss conditions that alter perception or imagination—conditions which aren’t often discussed from a neurological perspective. Few would say that a vivid dream or sudden burst of inspiration are primarily neurological matters, and might even think that applying neurology to such experiences devalues them. But Sacks will describe, without devaluing it, the mental achievement that can result from aberrations in the brain’s structure.
Part Three is the shortest part of the book, but it’s important in complicating the traditional understanding of a disorder as “something wrong.” Sacks proposes that, under certain conditions, a mental disorder could easily be construed as benign, or even as a gift. It’s often been suggested that some of the greatest creative geniuses in history had neurological abnormalities of some kind, and Sacks will investigate this notion. It’s worth noting that Sacks continues using the words “disorder,” “disability,” and “illness,” despite their pejorative connotations—connotations which, as Sacks makes clear here, he wants to challenge and complicate.