Abigail Adams wrote to her son John Quincy Adams in the midst of the American Revolution, suggesting that “the habits of a vigorous mind are formed in contending with difficulties. Great necessities call out great virtues.”

“Somehow he managed,” Lincoln’s most thorough modern biographer has concluded, “to be strong-willed without being willful, righteous without being self-righteous, and moral without being moralistic,” thus yielding a “psychological maturity unmatched in the history of American public life.”110 Which is simply to say that he managed polarities: they