Theatre is a live art form – and, as such, it's subject to alteration and improvisation and intervention at any given moment. Actors don't have to stick to the script – and neither do audiences. This is something that has scared certain people, particularly those in power, over the centuries.

Add Donald Trump to the millennium-long list of puritans and politicians afraid of the democratic nature of the free speech zone that is theatre.

Last night, American vice-president-elect Mike Pence got an earful as he attended Lin-Manuel Miranda's hit musical Hamilton on Broadway.

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Related: Pence says he's not offended by comments to him at 'Hamilton' show

Related: Trump demands apology after 'Hamilton' actor addresses VP-elect Pence from stage

First, the audience had its turn. According to reports, there were boos directed at Pence as he took his seat – and the cheers were exceptionally loud when the musical's signature line arrived: "Immigrants, we get the job done." George Washington's line "Winning is easy, young man, governing's harder" was greeted by more applause than usual by the audience, re-authoring a lyric Miranda penned written years ago into a dig at those about to move into the White House.

Actor Brandon Victor Dixon, currently playing Aaron Burr in the musical about the American revolution and its aftermath, then spoke to Pence directly during the curtain call. "We, sir, we are the diverse America who are alarmed and anxious that your new administration will not protect us, our planet, our children, our parents, or defend us and uphold our inalienable rights," he said. "We truly hope this show has inspired you to uphold our American values and work on behalf of all of us. All of us."

We haven't heard from Pence about how he received this epilogue yet – according to AP, he politely listened to it in full from the hallway outside the auditorium.

The President-elect, Donald Trump, however, took to Twitter to condemn the Hamilton cast for having "harassed" Pence. On Saturday morning, Trump tweeted: "The theatre must always be a safe and special place. The cast of Hamilton was very rude last night to a very good man, Mike Pence. Apologize!"

What happened at Hamilton is a sign not of rudeness, however, but of the theatre in rude health. Anyone who's a student of classical plays will know that prologues or epilogues directed at the "court" are a long theatrical tradition – and a little audience booing is pretty tame behaviour compared to the riots that have erupted at performances through the ages from Byzantium to New York in the 19th Century.

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Trump is half-right about theatre, however: It is a special place, but not a safe one.

There is nothing "safe" about gathering citizens together in the same physical space and having them listen to characters in conflict, that is, with different points of views. It's only seemed like it in the West for the past century or so as we've lived in societies that have embraced free, respectful speech and democratic debate in common areas like the mainstream media, now derided and dying.

Now, however, just how "special" theatre is has started to become clear again.

The Internet promised us a place where we would interact with people unlike us – but it's actually delivered the opposite. Facebook algorithms shove us into silos of like-mindedness, delivering us news articles and opinion pieces that match our worldview and turn us against our neighbours. Twitter's an echo chamber – and, on those rare occasions when those who disagree do come together on it, it's usually to hurl insults at one another rather than to try to understand one another.

Theatre is one of the few remaining places where citizens come face-to-face, sit side-by-side to hear ideas for an extended period of time. This is, of course, what made theatre revolutionary when it was born as an art form in Ancient Greece alongside democracy. The great innovation of theatre was to bring the concept of dialogue to storytelling – and the classics scholar Peter Burian has argued audiences learning to listen to characters present different points of view in the theatre paved the way to them listening to each other in democratic discourse.

We need that civics lesson again now. Hamilton's a great example of theatre's power to create empathy for those unlike us, or those we might disagree with. On one level, it is certainly a product of the Obama years in the United States – through its diverse casting and hip-hop score, comparing the young Americans of colour and immigrants of today to the Founding Fathers.

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But Hamilton also asks black actors and other actors of colour to play historical figures, none of them simple heroes, like the slave-owner George Washington. This is radically out of step with the political left's current call-out culture – asking us to step into another's shoes rather than judge them.

That is indeed unsafe to Trump and those like him who profit off the politics of division.