The question of what might have been hangs over the legacy of the Kennedy dynasty.
What kind of Presidency would JFK have delivered if he had dodged an assassin's bullets in Dallas in 1963?
He may have been able to live up to the hype and the heady optimism of the Sixties.
But it's also more than possible that disillusionment would have slowly set in, not least with the spectre of the Vietnam War looming.
Brother Bobby might have had similar trouble fulfilling the hopes and expectations that were being invested in him as he made his bid for the White House.
Ted Kennedy was also unable to realise his full political potential. In his case, though, it was down to his own actions.
The 1969 Chappaquiddick scandal helped derail his campaign for the Democratic nomination for the 1980 Presidential race.
Even if he had seen off Jimmy Carter for that nomination, the circumstances surrounding Mary Jo Kopechne's death would surely have been raised time and again in the ensuing |battle with Ronald Reagan.
Ted Kennedy's womanising and drinking antics damaged his standing in subsequent years. It led to him becoming a figure of fun and the butt of jokes on late night chatshows.
The legendary — and very sleazy — Mayor Quimby character on The Simpsons bears more than a passing resemblance.
His reputation improved in recent years as his private life became much more settled.
He will be remembered as a highly effective legislator with an ability to strongly champion causes and build political alliances to advance them.
To Democrats he was an inspiration — a standard bearer who kept the torch burning during the periods of Reagan and Bush.
In this small part of the world opinion was divided, to say the least. Irish Catholics have long regarded the Kennedys with great pride and affection. To northern nationalists Ted Kennedy was a leading friend of Ireland and an important contact in the US corridors of power.
But he was close to being a hate figure among many Ulster Protestants.
This writer can recall him being denounced as a “murderer” from a televised unionist platform in relation to Chappaquiddick.
Such sentiments seemed to fade over the years, and there was little or no controversy over his attendance at the May 2007 Stormont event to mark the return of power-sharing devolution.
Kennedy's own views on Ireland had evolved over time. He advocated a troops out policy at an early stage of the Troubles but subsequently became a close ally of John Hume and the SDLP. He supported the fledgling peace process in the 1990s, pressing for a US visa for Gerry Adams in the run-up to the 1994 IRA ceasefire.
The visa decision is described by pundits as a crucial building block and Kennedy had a key role in persuading President Clinton to make the move.
He was also highly critical of the John Major Government for its response to the IRA cessation.
Some 10 years later he snubbed Adams in Washington, instead meeting the sisters of Robert McCartney, the Belfast Catholic believed to have been murdered by members of the IRA in 2005. The symbolism of that stance was not lost on Sinn Fein or unionists.