[Janet Daley is a columnist for The Sunday Telegraph.]

So it's over. The Kennedy era, in which the political consciousness of most of my American generation was born, ends with a lingering illness and quiet mourning, so unlike the violent deaths of Ted Kennedy's elder – and greater – political brothers.

However much the youngest sibling may be lionised in the coming days, it was John and Robert Kennedy whose lives truly electrified American politics and whose assassinations almost certainly precipitated, as Norman Mailer once claimed, a national nervous breakdown. It was that catastrophic psychic blow, Mailer argued, that gave rise to the youth culture of the Sixties, with its bizarre mixture of high idealism and narcissistic pleasure – which, as it happens, was a particularly apt memorial (even if we didn't know it then) for the Kennedy dream. Having lived through that time at Berkeley, where we more or less invented what became the international student revolution, this analysis seems sound to me.

It is almost impossible to overestimate the impact that the presidential campaign, then the election victory, and then the murder, of President Kennedy had on an impressionable new cohort of Americans who were just emerging from the Eisenhower years, and a period of conformist stagnation. (Time magazine had called our immediate predecessors "the silent generation".)

All that hope, all that promise: the Peace Corps, the first official recognition of the goals of the civil rights movement, the truly magnificent rhetoric of the Kennedy speeches (don't
let anyone tell you that Barack Obama's speeches are anything like as fine) – and it was extinguished in what was then an unthinkable act.

The shock was literally staggering. I can still, to this day, recall it in all its visceral intensity, as can, I am sure, almost every one of my countrymen who was sentient at the time. When Bobby Kennedy, too, was struck down, there was an almost fatalistic sense of futility. Perhaps it was at that moment that the Sixties movements moved well and truly into their nihilistic phase. For there was still a belief then that these were two quintessentially good men who embodied the best intentions of the United States to live up to its own definition of virtue. That was, of course, before we learned the truth about their private lives.

Ted Kennedy's misadventure at Chappaquiddick is now remembered for its political significance in supposedly ending his presidential ambitions, rather than for the truly horrific fact that a young woman drowned because she was trapped in a car which Kennedy drove off a bridge (and from which he managed to extricate himself). That he was almost certainly technically drunk at the time, which helped to account for his unforgivable delay in reporting the incident, and that the following hours were devoted to a desperate scramble to cover it up, were too much even for a country that was inclined to give any Kennedy the benefit of the doubt.

But at that stage, we still did not know the half of it. Young Teddy was thought to be the weak link, the wild card: the inveterate adulterer and feckless drinker who simply hoped to ride the wave that had been created by his heroic brothers.

But oddly, even after we learned, in quite grotesque detail, of the discrepancy between the private and public morality of the senior Kennedy men – in John Kennedy's case, a compulsive sexual promiscuity that was close to pathological – and of the sordid arrangements that were made to procure hundreds of women for JFK by members of the family itself, the legacy was not utterly destroyed...