I found the first two parts of this book compellingly brilliant -- and had decided that the book was an allegory. The narrator of Parts I-II, who speaks in the first person, is not the author (note the ages/dates), but an exemplum of Japanese Modernity -- where Sensei is an exemplum of the Meiji period. But by the end of Part III, this interpretation was untenable, and the sheer neurosis of the story had begun to weigh on me. Hence the 4-stars (instead of 5).
The Emperor Meiji died in 1912; this book was written in 1914; Natsume Soseki died (at the age of 48) in 1916. I have this book, very highly recommended to me, on file -- dealing with Japan and WWI:
The final page of the book mentions Watanabe Kazan:
Watanabe Kazan (1793-1841): http://en.wikipedia.org/wiki/Watanabe_Kazan