McCullough’s main theme throughout Truman is the rise of the underdog. Truman’s seemingly miraculous transformation from a Missouri farmer lacking a college education to the president of the United States was, in the author’s view, the result of resilience, hard work, perseverance, and personal integrity. The concept of achieving success by pulling oneself up by the bootstraps is at the heart of American mythmaking. Throughout his life, McCullough argues, Truman “held to the old guidelines: work hard, do your best, speak the truth, assume no airs, trust in God, have no fear” (1118).

The author sets up this theme from the outset. He describes the young Truman as “an exceptionally alert, good little boy of sunny disposition” who liked all his teachers and did very well in most of his classes (39). He was respected by his peers, even though he was a hardworking “bookworm” rather than a cool, popular boy: “They wanted to call him a sissy, but they just didn’t do it because they had a lot of respect for him” (42). Yet even in his youth, he faced challenges due to poor eyesight: he could not participate in some sports and, later, he was rejected from West Point.