Historian David Donald once wrote a delightful essay called "Getting Right with Lincoln." It told, among other things, how Presidents in trouble over the last hundred years discovered a remarkable kinship to our greatest President.
Herbert Hoover, for instance, in 1932 journeyed to Springfield, Ill. As if it were the dark days of 1864, Hoover borrowed Lincoln's words for the war and declared that victory over the Depression was just a matter of fighting it out on "this line" if it took all summer. Franklin Roosevelt suggested that Lincoln was a father of the New Deal. Lyndon Johnson ran...