The particular combination of theme, packaging and timing that produces a best seller is always a mystery, and last year's top sellers in Japan presented even more of a puzzle than usual. What is it about "Baka no Kabe" by anatomy professor Takeshi Yoro that took it to the top of the chart soon after its publication in April and has kept it there ever since? Its basic premise -- that people tune out what they don't want to hear -- hardly seems an earthshaking revelation.

Some commentators cited its catchy title (literally, "the wall of a fool"), low price (680 yen), and unintimidating shinsho format (large print, convenient size, tasteful cover). Others saw a yearning for an authoritative figure to explain the "walls" they were encountering every day amid the shifting relationships between men and women, parents and children, older and younger generations, as well as between Japan and the world's political uncertainties.

Yoro himself (Asahi 10/28) attributes the steady sales of "Baka no Kabe," which has topped 2 million copies, to its conversational style, as it was based on his oral answers to questions from a Shinchosha editor. He sees a new style of Japanese emerging from the shukanshi (weekly magazine) writing style and the abbreviated sentences young people use when sending e-mail from their cell phones.