Was there ever a time when a technically sophisticated civilization reverted to an earlier, less advanced technology? There was, Japan, 1543-1879. During this period Japan effectively prohibited all manufacture of firearms and gunpowder, and isolated itself from the rest of the world with a blockade that remained successful until Commodore Perry's celebrated opening of Japan in 1854. An altogether fascinating book because Perrin is a consistently good storyteller, because even his footnotes are a delight to read, and because this story has few parallels in modern history.