The election of Donald Trump could be one of the best things that ever happened to American democracy.

We say this even though we believe that Trump poses a genuine danger to our republican institutions and has done enormous damage to our country. He has violated political norms, weakened our standing in the world and deepened the divisions of an already sharply torn nation.

But precisely because the Trump threat is so profound, he has jolted much of the country to face problems that have been slowly eroding our democracy. And he has aroused a popular mobilization that may far outlast him.

Many of the trends that led to Trump’s election have been with us for years; he has created a crisis by pushing them to their alarming endpoints. Political norms, for example, have been decaying for decades, but Trump has eschewed norms altogether. One reading is that there will be no going back from the diminished public life he has created, and it’s certainly true that the breaching of norms often produces a cascading effect: Behavior previously considered inappropriate is normalized and taken up by others. Yet Trump’s sheer disregard for the normal practices and principles of presidential behavior has cast a spotlight on the vital role that norms play in regulating and protecting our democracy. Only when norms disappear are we reminded of how important they were in the first place.