The thing which distinguishes Akira Kurosawa from other Japanese directors—I would go so far as to call it his great achievement—is precisely that he is first and foremost a director of ideas. Kurosawa is fond of insisting that every artist has, ultimately, only one theme. In his own case, he says, it is the question of why men cannot live together more happily and with greater good will than they do. Of course, one should be wary of swallowing whole such self-revelations by artists, since the artist is prone to self-delusion and self-misinterpretation in peculiarly complex and involved forms. Nevertheless, Kurosawa's remark can be taken at its face value insofar as it suggests that all his works are born, originally, of an idea. Whereas Japanese film directors in the past have leaned heavily toward naturalism, basing their work on a narrow, personalized experience, Kurosawa's style is...