The argument of this prodigiously detailed study is that Japan as we now know it did not exist until the late 18th century. It was then created, piece by piece, in response to a series of perceived threats. In answer to dissolution within and menace without, it was invented, formalized and identified as "Japan," and canopied by a presence that was defined as "Japanese culture."
The way in which this materialized is the theme of the work. "Sealing off the outside gave a unity to what lay within," observes the author, and he adds that the motivation for this reification of a "Japanese culture" was the establishment of a real entity "to counter a belligerent Other. It was fear-led."
The new "Japanese" entity was in many ways the creation of Matsudaira Sadanobu, the shogun's chief counselor. It was he who insisted upon what the author calls a "discourse of disaster," and through this organized dread assembled all of those talents who contributed to the self-conscious creation of a culture.