John Fitzgerald Kennedy was never much interested in analysing himself. "Poor Dick," he once laughed about his opponent in the 1960 US presidential election. "He has to get up every morning and ask, 'Which Nixon am I today?' But me - I know who I am."
Over half a century since Kennedy's shocking assassination, however, historians are still arguing over precisely what sort of man he was. Some laud him as the most charismatic politician of the 20th century, a gifted orator and statesman who saved the world from nuclear destruction. Others condemn him as a triumph of style over substance, a reckless playboy who left few real achievements behind and has been unjustly revered simply because he died so young.
The first clue to understanding JFK's character is that he lived life like an American aristocrat. Despite the family's humble Irish roots, the patriarch Joseph Kennedy was a ruthless, self-made millionaire who constantly told his nine children: "Kennedys don't cry", and "We only want winners around here." Jack was raised to leave his clothes on the floor for servants to pick up, rarely carried money because somebody around him would pick up the tab and scornfully dismissed Richard Nixon as a bad loser with "no class".
Another key factor is that throughout his life, Kennedy was a desperately sick man. Although he boasted to voters about his "vigour", he suffered constant pain from a variety of medical problems and had received the last rites several times before life-threatening operations. He fully expected to die young and often asked his wife Jacqueline to read him the poem, I Have a Rendezvous with Death by Alan Seeger.
Kennedy also grew up in a world shaped by war. His beloved older brother Joe was killed while flying a bomber plane in World War Two and he almost died himself when his torpedo boat was sunk by Japanese troops in the South Pacific. He showed great courage by guiding his crew to safety through the water and told a friend afterwards: "You've got to live every day like it's your last on earth."
All this helps to explain why Kennedy conducted his political career with such urgency. Instead of waiting his turn as tradition demanded, he ran for Congress immediately after the war and in 1960 became the youngest president ever elected. The 43-year-old exaggerated his mediocre record in the House of Representatives and Senate, blatantly lied about having Addison's disease and claimed authorship of a Pulitzer Prize-winning book called Profiles in Courage that had mostly been drafted by his speech-writer Ted Sorensen.
'A Time For Greatness' was Kennedy's self-explanatory campaign slogan. He dubbed his policy platform 'The New Frontier', signalling a decisive break with the past and promising to "get this country moving again". He narrowly defeated Nixon partly because his natural charm and quick wit came across so well on the relatively new medium of television.
Kennedy's presidency got off to a shaky start, vindicating the critics who had claimed he was too callow for the White House. His attempted military invasion of Cuba was an unmitigated disaster, which led to more than 100 anti-Castro soldiers being slaughtered at the Bay of Pigs.
He was woefully unprepared for the brutality of Soviet premier Nikita Khrushchev at their summit meeting in Vienna, prompting him to admit afterwards: "That was the roughest thing in my life… he just beat the hell out of me."
To Kennedy's great credit, however, he proved himself able to learn from those early mistakes. His finest hour beyond doubt was the Cuban Missile Crisis of October 1962, when he successfully faced down both Khrushchev and the US army generals who were baying for war. As Secretary of State Dean Rusk said at the crucial moment: "We're eyeball to eyeball and I think the other fellow just blinked."
Kennedy's other foreign policy successes included the signing of a Nuclear Test Ban Treaty and the creation of a Peace Corps that inspired more than 10,000 Americans to volunteer their services in developing countries. His domestic record was weak by comparison as he consistently failed to get legislation through a hostile Congress. He was initially slow to act on the civil rights issue, but did send federal troops to protect African-Americans who wanted to enrol in previously all-white universities. When most people think of JFK, however, it is the soaring rhetoric that they remember rather than any concrete action or policy. His best soundbites still echo down the years: "Ask not what your country can do for you, ask what you can do for your country"; "We choose to go to the Moon in this decade and do the other things, not because they are easy but because they are hard" and, most famously of all, "Ich bin ein Berliner."
Kennedy also brought a sense of style and glamour to the presidency that had never been seen before. Much of the credit was due to Jacqueline, who dramatically redecorated the White House and then gave US television viewers a tour of her work. At an official state reception in France, the president opened his speech by quipping: "I am the man who accompanied Jacqueline Kennedy to Paris."
Behind his family-man image, however, JFK was what would be described today as a sex addict. He regularly smuggled girlfriends into the White House, safe in the knowledge that Washington's deferential press corps would never dare to expose him. He once left the British Prime Minister Harold Macmillan flabbergasted by asking: "How is it for you, Harold? I get terrible headaches if I don't have a woman for three days."
Any assessment of Kennedy's legacy must be littered with unanswered questions. Would he have won a second term in 1964? Would he have pushed harder to secure equal rights for black people? Would he have scaled down the US presence in Vietnam or been sucked into the same quagmire that eventually destroyed Lyndon Johnson?
JFK's early death led to a massive outpouring of grief and ensured that history will remember him chiefly as a martyr who never got to fulfil his true promise. He himself would have been quite philosophical about this.
On November 22, 1963, he saw a full-page anti-Kennedy advertisement in the Dallas Morning News, turned to his wife and said: "You know, we're heading into nut country today.
"But Jackie, if somebody wants to shoot me from a window with a rifle, nobody can stop it. So why worry about it?"