Actually, Secrets of the Samurai is by Ratti and Westbrook. While they are good aikidoka, they are lousy historians. What they did was to compile everything they could find in English about the samurai. Some of it is really good, some of it is total crap. Unless you are well versed in Japanese history, you'll not know which is which. It makes for some interesting reading, but don't believe anything in it unless it is verified by a reliable source. Secrets of the Samurai is NOT a reliable source.