[Maya Angelou once claimed that] "Black men talk about change when what they really mean is exchange. They want to take over the positions of power white men have." Certainly Buck and the Preacher, the title characters in the new Sidney Poitier-Harry Belafonte film, would agree. The themes of exchange are obviously what appealed to Mr. Poitier when he chose the script for this black Western [Buck and the Preacher], which is his first assignment as a director. Poitier plays Buck as the latest word in self-reliant, soft-spoken, straight-shooting cowboys. At one point, while escaping a trap laid by his white nemeses, Buck even executes a running mount that would have made Yakima Canute proud. Yet I don't want to give the impression that Buck and his unscrupulous sidekick, the Preacher … are just Roy Rogers and Gabby Hayes in black face. There is also an undertone in the...