For all its economic troubles and political discontents, there is one arena of human striving in which Japan remains a colossus: the technology of the toilet. Even in these straitened times, Japanese lavatories remain the most advanced, the most luxurious and the most ingenious in the world.
These days, the "Warmlet" (with built-in heater in the seat) and "Washlet" (which directs a cleansing jet of water between the buttocks) are old hat. Japan's premier loo manufacturer, Toto, is developing a new generation of conveniences which will not only dispose of your waste, but also analyse it and submit the results electronically to your doctor.
So it was only a matter of time before this great Japanese theme found its historian: a 54-year-old civil servant, Shigenori Yamaji. Following his Toilet Archaeology and Notes on the Toilet, Mr Yamaji has recently published his third book, the 216-page Journal of Toilet Culture. Lavishly illustrated with photographs of unusual toilets encountered on his travels, rich in allusions to literature and myth, the book sets itself an unashamedly ambitious task: to view all of Japanese history through the prism of the lavatory.
Mr Yamaji's insights are inspired by the smallest details. Visiting a historic samurai house, he heads for its smallest room and is at first puzzled by a hook on the inside. Its purpose, he deduces, was to hang a sword - for the house's first owner was deeply involved in political intrigues. Nowhere was he free from the threat of assassination - hence the need to keep his blade on hand. "Even in the toilet," Mr Yamaji observes, "we can feel the tense atmosphere of the Bakumatsu period."
Other highlights include the revelation that, until the 19th century, Japanese women as well as men used to urinate standing up into street troughs which were channelled into the fields. "With the coming of chemical fertiliser, changes in underwear styles, and a growing feeling of embarrassment, the custom disappeared."
But the most moving part of the book concerns a visit to China, which even unfastidious travellers regard as the Hades of toilets. To Mr Yamaji, however, the open cesspits and partition-free communal loos of Beijing have a charm. "In China, everything is open and people don't worry about …