From Franklin Roosevelt on, U.S. Presidents are either mysterious or unmysterious. Among the uncomplicated, unmysterious characters: Harry Truman, Dwight Eisenhower, Gerald Ford, Jimmy Carter and George H.W. Bush. The others--Roosevelt himself, John Kennedy, Lyndon Johnson, Richard Nixon, Ronald Reagan and Bill Clinton (the jury is still out on George W. Bush)--confront a historian with odd opacities of character: neuroses, compulsions, contradictions or (in the cases of Roosevelt and Reagan) an impenetrable geniality. Reagan's biographer Edmund Morris concluded that the man's apparent depthlessness was itself an enigma, a kind of blank, like the whiteness of the whale.
In An Unfinished Life:...