Throughout history, certain photographs, such as Nick Ut's "Napalm Girl", have etched themselves forever into the public psyche. A recent photograph of Donald Trump is poised to join this club. Blood streaks his face. The American flag looms in the background. His fist raised in defiance. The photograph of Donald Trump taken by Associated Press photographer Evan Vucci in the aftermath of an assassination attempt in Pennsylvania on 14 July is gathering iconic status. To coin a phrase, the photo is "one for the history books", a defining symbol of an era plagued by political crisis, violence and upheaval in...