In 2018 Mark Leibovich wrote about the difficulty of covering a president whose motivations could rarely be distilled from cold logic. Understanding the average politician is easy—simply assume that their every action is devoted to winning their next election and you’ll predict their behavior 95 percent of the time. Understanding Donald Trump requires donning hip-waders and trudging through a bog of ego, grievance, rage, and insecurity with small mounds of rational strategic thinking scattered here and there.

Because of his, shall we say, mercurial nature, reporters had developed a habit of including reflections on Trump’s “mood” in their political analyses, Leibovich noted. We didn’t hear much about Barack Obama’s mood as president. We don’t hear much about Joe Biden’s, or Mitch McConnell’s or Kevin McCarthy’s for that matter. The Trump “mood beat” is a singular phenomenon driven by the uncomfortable fact that the 45th president is plainly, alarmingly unstable. Sorry: “mercurial.”

So when his behavior turns conspicuously more “mercurial,” it’s worth paying some attention.

Nine days ago America was treated to this spectacle at his rally in Ohio: