And now to quote Adam Gopnik

I liked Gopnik's article about the danger in Trump's appalling tweets, and it's worth reading it all.  But I think these are the key paragraphs:

The trouble is that the damage done by Trump’s words is damage enough. In a contestatory democracy—where the core notion, however debased by overuse and however degraded by money and power, is that political differences are settled by debate—words have, of necessity, a quality not so much sacred as practical. They’re the currency of open societies, which rest on the primary foundation of having exchanged weapons for ideas. There’s a reason that the great crises of this democracy have been met by an efflorescence of language, a reason that we turn to Hamilton and Franklin and Lincoln and King not just for wisdom about crises past but for a vocabulary for crises present. Words are what governments with a liberal public face have to live by. We know tyrannies by their temples; we know democracies through their tongues.

Trump’s words don’t debate or even discredit. They degrade and delegitimize. They’re insults so crude that it’s difficult to believe that anyone could find them persuasive, but that are clearly intended to appeal to a part of what is called the “base”—an unintentional, if somewhat Shakespearean, pun. One miserable truth of humanity is that cruel impulses are easy to awaken in large numbers of people, if they’re told by those in power that those impulses are now acceptable, and the form that such permission takes is invariably a reawakening of the language of demonology.....

Trump, in maintaining that the opposition is not merely wrong but criminal, not mistaken but illegitimate, undermines not a norm or a manner or some stuffy curlicue of liberalism’s house rules; he assaults its essence. We are shocked by Trump’s language not because we’re prim but because we understand intuitively, instinctively, that the language is itself an assault on the rule of law, not merely a prologue or preface to it. It’s not a puff of air. It has real consequences. James Comey registered this shock just the other morning on NPR: “President Trump, I don’t follow him on Twitter, but I get to see his tweets tweeted, I don’t know how many, but some tweets this past couple of days that I should be in jail. The President of the United States just said that a private citizen should be jailed. And I think the reaction of most of us was, ‘Meh, that’s another one of those things.’ This is not normal. This is not O.K. There’s a danger that we will become numb to it, and we will stop noticing the threats to our norms.” To which one might add only that it isn’t norms but premises that are being undermined. Every time Trump calls his critics or political opponents “crooks” or “slime balls,” it poisons the possibility for open debate.