It was the hair flip seen ‘round the world—and not in the Pantene commercial, Cher from Clueless, or Willow Smith kind of way. The video, as everyone knows by now, shows President Trump boarding Air Force One while the whipping Washington wind blows a flap of his flaxen hair away from his scalp to reveal a significant bald patch at the back of his head. The footage—now irreversibly seared into millions of brains—has sparked morbid fascination across the Internet. “Imagine this hair soaking wet,” my sardonic brother texted me. (Really, I’d rather not.) It has reopened the eternal mystery of “what even is Trump’s hair?” Is it real? Is it a Hair Club transplant? Who is responsible for the way it swirls around his head like a cone of fresh cotton candy?

But perhaps most of all, Trump’s follicle malfunction revealed that his hair truly is his Achilles heel, a soft spot in his super-macho, megalomaniacal m.o. He may be a “stable genius” in his own mind, but his hair is the one thing he can’t control—and one of the few things he can’t deny. And, tellingly, it’s the rare thing he generally declines to beat his chest and brag about—I’m sorry to remind you he once, on the Republican debate stage, not-at-all-subtly implied that neither his hands, nor his penis, are small. (Please make the unwelcome mental images stop.) But he offers far less passionate defenses for his hair, including, in 2013, that it “may not be perfect, but it’s mine.” Trump has further noted that he’s no Rita Hazan, disclosing in his book Trump: How to Get Rich that he colors his hair—albeit not well: “Somehow the color never looks great, but what the hell, I just don’t like gray hair.”

Is this the same man who looks at a patchy photo of the National Mall on his Inauguration Day and tells you he inspired blockbuster crowds; the very guy who decries the Russia investigation as “fake news” even as it indicts his former staffers for criminal offenses? The characteristic exclamation points, the all-caps declarations, and never-say-die defenses we’ve come to expect of Trump are conspicuously absent when it comes to his hair. He evidently saves that bile for other people’s physical appearances: for “Liddle” (sic) Bob Corker (who is 5-foot-7); for Mika Brzezinski, “bleeding badly from a facelift”; for Carly Fiorina’s face; and Rosie O’Donnell’s body. That Trump has yet to comment on the windy tarmac video—when he opines on everything up to and including Celebrity Apprentice ratings—or even spin it into the most compelling ad ever to always have a MAGA hat on hand, speaks volumes about the sensitivity of the issue. Trump has an answer, a retort, an excuse for everything—everything, it seems, but his hair.