What is the theme in The Best and the Brightest by David Halberstam?

One of the underlying themes is President Kennedy's need to prove himself. Kennedy was the youngest man to be elected to the position of President of the United States at the time. He felt that his age was a factor in his dealings in foreign affairs and felt a constant need to prove himself to be competent and tough. This was obvious in his summit meeting with Nikita Khrushchev when the Russian Premiere tried to bully the young U.S. President. Kennedy came away from the conference feeling that he had to prove that he was tough to the Soviets and that he was not going to let the Soviets push him around.