Was there ever a time when a civilization, technically sophisticated, and in full possession of its senses, reverted in an earlier, less advanced technology? You bet - 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 is the story that really has few parallels in modern history.