Commentary Fifty years ago this year, I attended a performance in London of a Zulu version of “Macbeth.” It impressed upon me that Shakespeare was, if not quite universal (I doubt that his plays would mean much to the uncontacted tribes of the Amazon jungle, for example), of very wide appeal across cultures. About a quarter of a century later, I attended a performance of “Macbeth” in which the title role was played by a black actor, alone among the cast. At first, I found this slightly disconcerting, but he was so good an actor that I soon forgot my initial feeling of strangeness. Since then, virtually all productions of Shakespeare that I have seen include black actors and actresses, who are dotted about the cast. All Ophelias are now black, often dressed in torn jeans, while Polonius generally remains white. For some reason which I cannot fully explain, I …