PHILADELPHIA, Pennsylvania -- For all the oft-derided journalistic hype about defining moments and game-changers, occasionally there are points in a campaign when the pendulum dramatically changes direction.
And when the history of this strange and frightening political year is written, 150 minutes in Philadelphia may have made all the difference. Three speeches by Joe Biden, Michael Bloomberg and, most of all, Barack Obama proved that the Democrats could find persuasive arguments and the proper tone to oppose the authoritarian demagoguery of Donald Trump.
Leading up to prime time Wednesday night, the biggest question hanging over this convention was not about the otherworldly truculence of Bernie Sanders' dead-end delegates. It was whether the Democrats could break the Trump code.
The bilious billionaire has often appeared impervious to normal political attacks. Trump often seems like a cartoon character who has jumped off a cliff, but won't fall because he has vowed never to look down. Not even embracing Russian espionage against State Department emails seemed likely to deter his supporters.
Then, Biden changed the equation by violating some of the norms of convention speechmaking. In a masterful address, the vice president taught an oratory lesson to political shouters (take note: Cory Booker and sometimes Hillary Clinton) about the emotional power of strong words delivered softly.
Waving off applause ("Just listen to me without booing or cheering"), Biden said in hushed tones about Trump, "This is a complicated and uncertain world we live in...[And] no major party nominee in the history of this nation has ever known less [and] has been less prepared to deal with our national security."
No one would ever call Michael Bloomberg an orator. Or a Democrat. But as one of the richest men in the world (net worth: $48 billion), Bloomberg makes Trump look like the real-estate guy who owns Baltic Avenue in a game of Monopoly. That alone granted Bloomberg the rare power to punctuate Trump's braggadocio.
And that's why there was heft to such Bloomberg put-downs as, "Trump says he wants to run the nation like he's run his business. God help us." And then there was the critique that probably most rankled Trump, with his claims to dubious billions: "Truth be told, the richest thing about Donald Trump is his hypocrisy."
It was nearly 11 p.m. in the east when Barack Obama took the stage for the fourth time at a Democratic convention. In his swan-song address as president, Obama followed in the footsteps of Ronald Reagan (1988) and Bill Clinton (2000).
These events pose a special set of challenges for White House speechwriters. For how does a president pass the torch while simultaneously reminding the world that his tenure in office will never be equaled? And how does a retiring president mount a partisan attack while still appearing to have moved beyond the pettiness of electoral politics?
At first it seemed like Obama was following the familiar script as he boasted of "all we've achieved together." That was in keeping with Reagan's self-congratulatory rhetoric: "Eight years ago, we met at a time when America was in economic chaos, and today we meet in a time of economic promise." And in 2000, Clinton said the same thing about his two terms in office, but used many more words.
Another important ingredient in the swan-song speech is slightly awkward praise for the president's successor. Reagan described George H.W. Bush as "someone who...can cut to the core of an issue." And Clinton struggled to convince the nation that "the greatest champion of ordinary Americans has always been Al Gore."
But Obama set off on his own rhetorical course when he harked back to his 2008 primary race against Hillary Clinton: "She was doing everything I was doing, but just like Ginger Rogers it was backwards in heels."
At times, though, Obama drifted back to the standard-issue rhetoric of political praise. "I can say with confidence," Obama declared, "there has never been a man or a woman -- not me, not Bill -- more qualified than Hillary Clinton to serve as president."
That was akin to Reagan praising his successor, George Bush, as "experienced enough" to negotiate with the Soviet Union because "this is no time to gamble with on-the-job training."
But what made Obama's speech so politically memorable was that he was unafraid to go after Trump by name. Unlike Reagan and Clinton who only obliquely referred to the other party in their farewell convention speeches, Obama sneered, "The Donald is not really a plans guy. He's not really a facts guy, either."
But the most powerful portion of the speech was not the cracks about Trump's "trail of lawsuits and unpaid workers and people feeling like they got cheated." Rather, it was when Obama went further by suggesting that Trump in his scorn for the nation's institutions is antithetical to America.
In a passage designed to attract wavering Republicans appalled by Trump's fear-mongering, Obama said, "Ronald Reagan called America 'a shining city on a hill.' Donald Trump calls it 'a divided crime scene' that only he can fix."
It was a rhetorical trick worthy of the Gipper, using the other party's hero to discredit its current nominee. It was in keeping with Obama's earlier remark that the Cleveland convention "wasn't particularly Republican and it sure wasn't conservative."
There is always a risk in over-reacting to convention oratory by believing it will remain embedded in the minds of the voters in November. But I am willing to gamble that this was the night that the suddenly nervous Democrats found their voice and the arguments that will carry them to Election Day.
Roll Call columnist Walter Shapiro is a veteran of Politics Daily, USA Today, Time, Newsweek and the Washington Post. His book on his con-man great-uncle was just published: "Hustling Hitler: The Jewish Vaudevillian Who Fooled the Fuhrer." Follow him on Twitter @MrWalterShapiro.