Joe Biden spoke of advice from his mother, who taught him to be 'scrappy'
If you want to make one of those convention speeches that everyone remembers you need wit, passion and a flair for language - and a little influence over who they invite to deliver the warm-up address.
I doubt very much that Joe Biden had any say in the selection of Bill Clinton to address a packed convention centre in the hour before he went onstage himself.
Mr Clinton, who had begun to appear irascible and frustrated as the nomination slipped from his wife's tenacious grip, was in magisterial form, demonstrating the real orator's gift of whipping the crowd into a frenzy without abandoning his own calm demeanour.
In American political parlance, he delivered.
He lacerated the Bush administration, praised Republican John McCain's courage while rubbishing his credentials for the presidency and finally said simply what Mr Obama's strategists must have started to fear he'd never say at all: "Barack Obama is ready to be president of the United States."
It restored Mr Clinton's standing in the Democratic Party, which had been slightly dented by his previously churlish attitude towards his wife's rival - and it incidentally reminded the audience, as he no doubt intended, that if the American constitution allowed presidents to run for a third term, he'd probably win again this time.
Mr Biden can probably live with the thought of being upstaged by the most successful Democrat since World War II, but he must have been taken aback by the assurance and power with which his own son, Delaware's Attorney-General Beau Biden, introduced him.
Barack Obama and I took very different journeys to this destination, but we share a common story
Senator Joe Biden Democratic vice-presidential nominee
The younger Mr Biden told the story of the road accident that killed his mother and his infant sister and how his father had considered abandoning a newly-won seat in Congress to bring up his two young sons.
He paid moving tribute to how Joe Biden decided instead to take his seat and commute every day from Washington DC to the family home in Wilmington, Delaware, to allow him to raise his sons.
Most introductory speeches at conventions are rather perfunctory affairs, but I saw several people wiping away tears as Beau Biden introduced his father with the words: "My friend and my hero."
Mr Biden Senior did a pretty good job in the end - assisted by an audience who were desperate to make it look as though he was doing a brilliant one.
Vice-presidential nominee Joe Biden on 'the extraordinary' election
The best personal passages were addressed to his mother, who was sitting in the audience.
He quoted the advice she used to give him when he came home with a bloody nose as a little boy in the scrappy town of Scranton, Pennsylvania.
He said: "When I was knocked down by kids who were bigger than me, she'd send me back out and say 'Bloody their nose so you can walk down the street the next day'."
That's one reason, of course, why Mr Biden is on the ticket. His roots are in the rustbelt towns of the north-eastern US among blue-collar Catholics.
That's a constituency which hasn't really warmed to Mr Obama yet and Mr Biden reminded them, without any great subtlety, that he is one of their own; smart and sophisticated these days, but still scrappy.
On the attack
The other reason Mr Biden got the pick was his long experience in foreign policy issues - to put it bluntly, he papers over a hole in the Obama resume.
Joe Biden papers over the foreign policy hole in Barack Obama's resume
He talked about the difficult decisions America has faced - still faces - on troop levels in Iraq and Afghanistan; it was one of a number of issues where he finished a description of a problem with the words: "John McCain was wrong, and Barack Obama was right."
He had another catchphrase lined up too, which you'll be hearing quite a bit in the next few weeks... offering a summary of a McCain policy - or at least his view of it - and then dismissing it with the words: "That's not change, that's more of the same."
The speech was more about a personal narrative than high politics but the Democrats have decided to use the convention to introduce us to the Obama and Biden families, rather than immerse us in micro-economics or strategies for the Middle East.
Mr Biden did enough to demonstrate why he was chosen, although his attempts to avoid being upstaged weren't exactly helped when Barack Obama appeared at the end of his speech to excite the crowd, just as Bill Clinton had before it started.
I suspect there is more to come from Joe Biden, who wasn't quite in vicious attack dog mode that some of the delegates I spoke to had been expecting.
But he did show us flashes of that scrappy kid from a tough part of town and that is why he's on the ticket: to follow his mother's advice - pick yourself up and give the other guy a bloody nose.
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