Last week, a man armed with an assault rifle was apprehended on a southern Florida golf course. He was planning to murder Donald Trump on the links. It was the second near miss in two months. It seems likely that the shooter, Ryan Routh, was acting alone. But he is not alone in the hatred he has for Trump. He shares that with millions of Americans. In many people’s eyes, the 45th president of the United States is an existential threat to our republic. And ever since Trump won the Republican nomination for president in 2016, his opponents have treated him as such.  They were shocked because Trump broke many of the rules of modern politics. From the minor to the unprecedentedly major. This dynamic between Trump and his haters has changed the chemistry of American politics. In 2016, Trump shocked the country when he led rallies where his adoring fans chanted, “Lock her up.” Eight years later, crowds chant “Lock him up” at Kamala Harris’s rallies. In this respect, Routh is part of a larger problem that is tearing our country apart. When the other side vying for power is considered so beyond the pale, the norms of political decorum and fairness are worth breaking to stop an opponent that threatens our very system. You hear it from both parties. Trump is an “extinction-level event.” If Kamala wins, our country will become “Venezuela on steroids.”  One escalation begets the next, until the old customs and rules of our politics have changed forever. We take it for granted today that we settle our elections with voting and not shooting. But republics don’t last forever. And when they fall, violence almost always follows.  What leads a republic to choose the gun over the ballot? Because it doesn’t happen all at once, at least if history is any guide. In ancient Rome, the rule-breaking of one man—and the response of his enemies—created a crisis from which the Roman republic never really recovered. His name was Tiberius Gracchus. And while they were different in many ways, he was the Donald Trump of his day.  Tiberius, like Trump, was an elite who turned on the elites, a class traitor who channeled the resentments and anger of the common man against a system rigged against him. Both men disregarded the unwritten political rules of their era. And, in turn, those norm violations prompted their enemies to disregard the rules themselves. In Rome, this cycle led to bloodshed and eventually the death of the republic itself.  In America, we remain a republic, for now, but the cycle of escalations between Trump and his opponents strains our foundations like no political crisis since the civil war. Today, Eli Lake explains what the beginning of the end of the Roman republic tells us about the fate of our own republic. Learn more about your ad choices. Visit megaphone.fm/adchoices