Like other great figures of 20th-century American politics, Lyndon Johnson defies easy understanding. An unrivaled master of vote swapping, back room deals, and election-day skulduggery, he was nevertheless an outspoken New Dealer with a genuine commitment to the poor and the underprivileged. With aides and colleagues he could be overbearing, crude, and vindictive, but at other times shy, sophisticated, and magnanimous. Perhaps columnist Russell Baker...