Was it only two weeks ago that the white-haired, perma-smiling Ariel Sharon took his leisurely survey of the Temple Mount - the Haram al-Sharif in the heart of Jerusalem's Old City? Has it really taken only two weeks to bring us from what seemed to be the brink of lasting Israeli-Palestinian peace to the abyss of Middle East war?
As we counted down the final months of the Clinton administration, we observers of the diplomatic cut-and-thrust noted that time was running out, that a window of opportunity was closing, that a committed President was becoming a lame-duck President, that Mr Barak was haemorrhaging support, that Mr Arafat was going to have to make some hard decisions fast. Yesterday, time did run out, the window slammed shut. And as for the future, the only safe bet now is that things could get a lot worse and will take a long time to get any better.
In retrospect, to put it mildly, Mr Barak might have been better off ignoring the calming assurances of his security chiefs - who had apparently been in contact with their Palestinian counterparts - to the effect that Mr Sharon's visit, while perceived as provocative, as the symbolic reconquest of the Mount, would not produce a particularly angry reaction from the Palestinian or the Israeli Arab public.
But, also in retrospect, perhaps both Mr Barak and the Clinton administration erred, fatally, two months earlier at the Camp David peace summit, in trying to force the Palestinian Authority President Yasser Arafat to compromise, there and then, on the status of Jerusalem. A final Israeli-Palestinian peace was always going to leave both sides dissatisfied with their stake in the holy city.
While Mr Barak was ready to risk the wrath of his own people by offering to share control, taking that risk in the full awareness that his mentor, Yitzhak Rabin, had been murdered by one of his own people for far less dramatic peace moves in the West Bank, Mr Arafat plainly was not. More patience, more limited objectives, might have earned their reward further down the line.
The Israeli claim is that Mr Arafat seized on the Sharon visit as a pretext, a means to abrogate his commitment to resolve all disputes at the negotiating table, and to stir up his own people into the street protests that, met by an unyielding Israeli military response, have brought us to this nadir.
The Palestinians' insistence is that Mr Barak could easily have prevented Mr Sharon's visit, that their public outpouring of rage was genuine and spontaneous, and that there was no way to calm it once Palestinian blood was being spilled with such apparent indifference by the Israeli troops.
The death toll - more than 90 fatalities, almost all Palestinian - tragically bolsters the Palestinian claims. So too does Mr Barak's readiness to widen his governing coalition to include Mr Sharon. But the relentless footage screened hour after hour on Palestinian TV, of Palestinian suffering at Israeli hands, some of it mischievously edited, underlines the Israeli assertions of deliberate incitement.
And the release from jail by Mr Arafat of the expert bomb-makers from Hamas and Islamic Jihad, and the presence of representatives of these militant movements at his leadership meetings, is all the evidence Israelis need that he has no interest in reconciliation.
Left to themselves, there is absolutely no prospect of Mr Barak and Mr Arafat putting a stop to this escalating conflagration. Astoundingly, each in turn has also flatly rebuffed Mr Clinton's efforts to broker a ceasefire in the past few days. Lame-duck president, indeed.
So our eyes now turn to Amman and, especially, to Cairo - the capitals of the two countries formally at peace with Israel.
The majority of Jordan's four million population is itself Palestinian, and the young King Abdullah is already under pressure to do more than donate a pint of his own blood for the Palestinian cause. Egypt's President Hosni Mubarak is grappling with intensifying student protest, and has his own fair share of Islamic extremists.
But it is on the actions of these two leaders that the scale of this conflict now depends - the choice between a limited confrontation between two embittered protagonists, or a full-scale regional war.
Eventually, Israel and the Palestinians will have to sit down again to try to divide this bloody territory. The fighting, however many people now have to die, will not resolve anything.
But will the entire Middle East have to go to war first?