Whenever academics and scholars tickle their fancy by putting forth yet another poll of historians on presidential rankings, there is little doubt about which president will top the list—Abraham Lincoln. In the numerous such polls executed since Arthur M. Schlesinger Sr. pioneered the genre in 1948 for Life magazine, Lincoln has come out as number one in nearly all of them. Of the seven surveys I pulled together for my 2012 book on the subject, Where They Stand, the Illinois rail-splitter was judged the nation’s greatest president in six of them. In the seventh (a 2005 Wall Street Journal poll), George Washington came out on top, with Lincoln in second place. (Franklin Roosevelt almost always occupies the number three slot.)As the nation prepares to observe Memorial Day, it might be a fitting time to ponder just what constituted Lincoln’s greatness. One could begin with his personal qualities and note the encomium of the political historian Thomas A. Bailey of Stanford. Lincoln, he wrote in 1966, was “undeniably a great man…in spirit, in humility, in humanity, in magnanimity, in patience, in Christlike charity, in capacity for growth, in political instincts, in holding together a discordant political following, in interpreting and leading public opinion and in seizing with bulldog grip the essential idea of preserving the Union.” What Bailey seems to be saying is that Lincoln was a political genius who also happened to be saintly.