The title is a reference to not only a sudden wave of interest and influence, but the famous Hokusai woodblock print, which has become one of the stock images of classical Japanese art.
The Japanese archipelago was closed to all foreigners (on penalty of death) until Admiral Matthew C. Perry's "kurofune" (black ships) forced open Tokyo Bay in 1854. This triggered a revolution in political and social thought within the Emperor's inner circle- the "Meji Restoration", which now placed top priority on modernizing the Japanese economy and military. Japan was now open for visitors. During the belle epoque from 1870 to World War I, it became a favored go-to destination for scholars, adventurers, and artists, who couldn't get enough of this new and novel, previously-unknown culture. The book follows some prominent Westerners who made the journey, observed Japan, and brought something of what they had seen to their countrymen. To a lesser extent, the book also follows emissaries from Japan who traveled to the Occident and became minor celebrities.
The Great Wave is not overly scholarly; it's basically a period piece, showing how bits and pieces of Japanese culture were eagerly consumed and imitated by the West- mainly by the United States. The one thing that came as a surprise to me was how Boston was the undisputed epicenter of the early 20th century American obsession with Japan. Socialite/art collector Isabella Stewart Gardner funded numerous purchasing expeditions, and even today, the Boston Museum of Fine Arts and the Isabella Stewart Gardner Museum have the most extensive collections of Japanese classical art outside of Japan. Many of the other luminaries mentioned in this book were in Gardner's social orbit during this time: zoologist Edward Morse (Boston University has an auditorium named after him), astronomer Percival Lowell (whose discovery of trenches on Mars led to the popular belief that intelligent life must have dug these canals; thus fueling H.G. Wells to write "War of the Worlds"), and the sexually... uh, "open" astronomer/author power couple David and Mabel Todd (Mabel wrote Emily Dickenson's biography). Herman Melville is also mentioned.
To be honest, the book didn't exactly knock my socks off, but it was interesting to see how much cultural cross-pollination occurred between Japan and the US before World War I. Since the end of World War II, Japan and the US have shared a very close relationship- in part because the US occupied Japan, and set up many of its modern-day institutions, modeled on our own image. This book corrected my own misconception that the two nations hadn't been particularly close before then.