All politics is theater, but some parts are more theatrical than others.

The nominating conventions have become pure theater. Once upon a time the conventions chose candidates for the presidency, but now we have primaries and caucuses to do that.

The conventions could easily be dispensed with. They are vastly expensive and can be pretty darn boring. But they still exist because, like theater, they entertain.

They are live events where the most beautiful people in our society — the network anchors and TV reporters — parade before us.

Simon Rosenberg, who runs a left-wing think tank, told reporters recently: “I think part of what’s going on in this election is that Americans are bored with politics, and at least Donald Trump is interesting. What the Clinton campaign has to do is not make him interesting but make him threatening.”

That both Trump and Hillary Clinton have the highest negative ratings among those who ran for president in both major parties this year seems to be telling us something. Maybe it’s: We don’t need to like them. We just need to get a kick out of them.

The Republicans had their opportunity to get a kick out of Clinton last week — do the shouts of “Lock her up! Put her in stripes!” still linger in the air of Cleveland? — and how fitting it was for an actress, America Ferrera, to have one of the more memorable lines in Philadelphia: “Donald’s not making America great again. He’s making America hate again.”

But the Democrats choreographed their four days wisely. Powerful speeches in the beginning and then some compelling life stories and then Hillary’s speech.

The final night seemed a flop until about 9 p.m., when a man named Khizr Khan, a Muslim immigrant whose son died saving the lives of 10 of his fellow soldiers in Iraq, came to the stage. Khan took a slim volume from his suit coat pocket and addressed Trump: “Have you even read the United States Constitution? …

“You have sacrificed nothing — and no one. … We are stronger together. … I ask every patriot American, all Muslim immigrants and all immigrants to not take this election lightly. … On Election Day, take the time to get out and vote. …

“Hillary Clinton was right when she called my son ‘the best of America.’ If it was up to Donald Trump, he never would have been in America.”

And he never would have gone to Iraq as a U.S. soldier and saved 10 lives.

Clinton was the star of the evening, of course, and though her voice lacked the power and richness of either her husband’s or Barack Obama’s, it was plenty good enough — especially for moments such as this one, when she said:

“My mother, Dorothy, was abandoned by her parents as a young girl. She ended up on her own at 14, working as a housemaid. She was saved by the kindness of others. Her first-grade teacher saw she had nothing to eat at lunch and brought extra food to share the entire year. The lesson she passed on to me years later stuck with me: No one gets through life alone.”

Earlier in her life, when Dorothy was just 3 or 4, her parents would leave her for days at a time and tell her to go to the corner cafe for food. A biographical film of Clinton, narrated by Morgan Freeman, had shown a picture of her mother as a child — she was a tiny thing — and you could imagine this young child, all alone and frightened, having to walk out at night and get food.

And that made it easier to understand Clinton and what drives her and what toughens her.

“In the end, it comes down to what Donald Trump doesn’t get: America is great because America is good,” she said. “So enough with the bigotry and the bombast. Donald Trump’s not offering real change. He’s offering empty promises.”

Some Trump people thought facing a woman would be easy. They thought wrong.

“Do you really think Donald Trump has the temperament to be commander in chief?” Clinton said. “Donald Trump can’t even handle the rough-and-tumble of a presidential campaign. He loses his cool at the slightest provocation — when he’s gotten a tough question from a reporter, when he’s challenged in a debate, when he sees a protester at a rally. … Imagine him in the Oval Office facing a real crisis. A man you can bait with a tweet is not a man we can trust with nuclear weapons.”

So much for Trump.

She concluded: “I know that at a time when so much seems to be pulling us apart, it can be hard to imagine how we’ll ever pull together. But I’m here to tell you tonight progress is possible. I know because I’ve seen it in the lives of people across America who get knocked down and get right back up.”

A few moments later, she was finished and the roars began. Her running mate came out on the stage, and then Bill Clinton — his eyes red from crying — came out and gave her a hug that seemed as if it would go on forever.

And she didn’t seem to mind that one bit.

Roger Simon is Politico’s chief political columnist. His new e-book, “Reckoning: Campaign 2012 and the Fight for the Soul of America,” can be found on Amazon.com, BN.com and iTunes.

Photo: A combination photo shows Republican U.S. presidential candidate Donald Trump (L) in Palm Beach, Florida and Democratic U.S. presidential candidate Hillary Clinton (R) in Miami, Florida at their respective Super Tuesday primaries campaign events on March 1, 2016. REUTERS/Scott Audette (L), Javier Galeano (R)