The United States has had, prior to Donald Trump, 44 presidents. (Arguably we’ve had 43, but the guardians of historical pedantry long ago decreed that Grover Cleveland, who served nonconsecutive terms, would be counted as two.) There’s no reason our descendants shouldn’t enjoy at least another 44—and, one hopes, even more.

But there’s also no reason to assume the American experiment in self-government will chug along forever, automatically and unproblematically. Abraham Lincoln commented in 1838 that if the experiment were to fail, the danger would “spring up amongst us. .  .  . If destruction be our lot, we must ourselves be its author and finisher. As a nation of freemen, we must live through all time, or die by suicide.” Lincoln did not believe that destruction would be impossible. To the contrary, he was concerned in 1838 that we might be drifting toward such an outcome. “I hope I am over wary; but if I am not, there is, even now, something of ill-omen, amongst us.”