The question has been asked so many times over the past 16 months of this presidential election that it has become a cliche: Has anyone ever seen anything quite like this? And yet, once again, Donald Trump took Campaign 2016 to places no one could have imagined when it all began.
What occurred yesterday is likely to be remembered as the Spectacle in St Louis: a presidential debate wrapped inside a sordid and unfolding series of events that have left Trump isolated, defiant and politically wounded, his Republican Party at war with itself and the country caught up in a campaign that has left issues and even moderately civil debate far behind, almost an afterthought.
In the wake of the release of an 11-year-old video of Trump speaking of actions that, if carried out, would amount to sexual assaults of women, the Republican nominee may have stepped back, issued another apology and tried to keep his demeanour in his exchange with Hillary Clinton as restrained as possible. He chose to do otherwise.
By the time the 90-minute town-hall debate had ended, he tried to turn attention away from the damaging video by saying that Clinton's husband, Bill Clinton, had treated women far worse. And he pledged that if he becomes president, he would appoint a special prosecutor to go after her for her use of a private email server, saying if he were in charge of law enforcement, she would be in prison.
Clinton said the Trump who appeared in the lewd video is the real Trump, a man who has insulted and denigrated women, Hispanics, disabled people, Muslims and others, and who is temperamentally unfit to be president. It is an oft-stated charge, but one with heightened effect at this particular moment of the campaign.
It's not that serious issues were not addressed and at times serious disagreements aired, whether it was over the Affordable Care Act or the state of US foreign policy under President Barack Obama.
But never has there been a debate in which the attacks, the body language or the exchanges conveyed the degree to which this campaign has reached the depths of division and disagreement, not just between the two candidates but between two Americans.
Put aside the effect of the debate on the campaign. There is time enough to assess that, but in many ways that was a secondary consideration. Instead, the larger implication of what unfolded was a debate unlike any ever seen in modern American politics, two candidates who have the utmost disrespect for the other hurling allegations, accusations, insults and criticism at each other.
If Trump had a strategy for the night, it was to embrace the view of those who have been calling on him not to apologise, not to appear defensive in the face of the latest controversy, but rather to go on offence, to throw whatever he can at Clinton in an effort to energise Americans who have been utterly loyal to him and who hold the Democratic nominee in contempt. It is a risky strategy, but it seemed likely to foreshadow the final four weeks of the campaign.
Most of the fireworks took place in the first half of the debate. By the second half, the personal insults receded slightly and it was during these exchanges that Trump sought to press his case that Clinton is a symbol of a failed status quo and that he offers not only alternate policies but also would blow up that status quo with an entirely different style of leadership.
Those are the arguments that Trump hopes will motivate enough fed-up voters to give him the presidency. They also could make some Republican leaders think twice before they leave him. If he accomplished that, then the night can be counted as partially successful for him.
But the strategy he employed overall is high risk, one that could limit his ability to expand his support and one that also risks offending those in his party who are now deciding whether to stick with him for the duration of the campaign.
Twenty-nine days remain until the election, and given this unbelievable year, no one can begin to predict the ebbs and flows to come, nor can the Clinton team take for granted the margins by which she now leads her rival. Should the spotlight turn to Clinton in a negative way, she could suffer politically as she has at different times earlier.
But Trump is a battered, bruised and angry candidate, and therefore more unpredictable than ever. What he staged before the debate even took place, assembling women who have accused Bill Clinton of sexual assault or Hillary Clinton of misconduct in the defence of her husband to appear before a group of reporters and photographers, was as audacious as it was unprecedented. And then he brought them into the debate hall.
Normally, presidential debates are the dominant events in the late stages of a campaign, something that freezes perceptions in the days ahead and shapes them in the days immediately following. Yesterday's debate was merely a part of a continuing story of a Trump candidacy in crisis and a Republican Party in turmoil generated by the release of the video.
That means it won't just be reaction to Trump's performance in the debate that will affect the campaign in the coming days. Voters will continue to draw their conclusions about his fitness to serve as president apart from how he looked and sounded on the stage in St Louis. And while a rebound is possible, further slippage, or even status quo, could prove politically fatal, given the precarious state of his candidacy.
Meanwhile, Republican elected officials will make their own assessments of his and the party's future in the context of the lewd video - and everything else they have endured from Trump both before and since he became their presidential nominee. In the hours before the debate, the list of GOP officials abandoning him continued to grow, and there's little reason to doubt some continuation in coming days.
Almost no matter how they judge the way Trump handled himself against Clinton, more GOP officials are likely to withdraw their support for him or call for him to step aside, however messy that latter would be. Instant polls could be less significant in affecting Trump's institutional support than the broader judgments of politicians about the potential effect of his candidacy on the party over the longer term.
Some Republicans are saying publicly that recapturing the White House is a lost cause, that Trump is so weakened that it's too late for him to repair the damage. Their goal will be to protect their majorities in the House and the Senate. But their efforts are likely to intensify a growing civil war within the GOP - as the hostile reaction by Trump loyalists to some of those who split with him underscored.
That civil war now pits a Republican establishment that is repulsed the more it sees and hears from Trump against a segment of the party that supports the nominee and is alienated as never before from the establishment. Ironically, that same establishment that now recoils from Trump helped foster the conditions that allowed him to seize the nomination earlier this year.
In one way, Trump showed yesterday that he knows he is now a candidate alone, on his own to fight the remainder of the campaign without the full support of his party.
If the past three days are any indication, it will be a wild and unsettling four weeks. But he also sought to send messages of reassurance to still-wavering Republicans that he embraces some of the priorities they hold most dear, whether on repealing Obamacare or naming conservative judges to the Supreme Court.
The final presidential debate won't come for more than a week - October 20 in Las Vegas. But its significance could pale in comparison to what happens in the days immediately ahead. Events are moving far too quickly and the stakes - for Trump personally and for the Republican Party - far too large for anyone to wait.
For Trump, this is a final roll of the dice. For Republicans this is about more than the presidency and they know they will be living with the fallout from this campaign long after the results of this election are known on the night of November 8.